# A 10 kg block slides down a frictionless slope which is at angle = 29 . Starting from rest, = 29 . Starting from rest,= 29 . Starting from rest,= 29 . Starting from rest,

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**Physics 221**

An object starts from rest at the origin and moves along the x axis with a constant acceleration of 4m/s^2. Its average velocity as it goes from x=2m to x=8m is: A. 1m/s B. 2m/s C. 3m/s D. 5m/s E. 6m/s An object is released from rest and falls a distance H during the first ...

**Physics**

A 0.2 kg hockey puck is placed against a spring lying on a horizontal frictionless surface. The spring is compressed 0.2 m, with the hockey puck, and then released. The hockey puck when released is able to go up a frictionless slope with an angle of 30 degrees to a height of 0...

**physics**

A crate of mass m (=40 kg) is placed at rest on a (frictionless) inclined plane, which has an angle (= 30o) above horizontal. a.) The force of gravity on the crate is: b.) The normal force on the crate is: size: N c.) The net force on the crate is: size: N direction: d.) How ...

**physics**

A simple harmonic oscillator consists of a block of mass 4.40 kg attached to a spring of spring constant 110 N/m. When t = 1.00 s, the position and velocity of the block are x = 0.126 m and v = 4.120 m/s. (a) What is the amplitude of the oscillations? What were the (b) ...

**physics**

A simple harmonic oscillator consists of a block of mass 4.40 kg attached to a spring of spring constant 110 N/m. When t = 1.00 s, the position and velocity of the block are x = 0.126 m and v = 4.120 m/s. (a) What is the amplitude of the oscillations? What were the (b) ...

**Physics**

Three blocks rest on a frictionless, horizontal table (see figure below), with m1 = 8 kg and m3 = 20 kg. A horizontal force F = 101 N is applied to block 1, and the acceleration of all three blocks is found to be 3.5 m/s2. Find m2. What is the normal force between blocks 2 and 3?

**General Physics**

A 2.3 kg block is initially at rest on a horizontal frictionless surface when a horizontal force in the positive direction of an x axis is applied to the block. The force is given by F with arrow(x) = (2.6 − x^2) N, where x is in meters and the initial position of the ...

**Physics**

A block of mass m1 = 6.25 kg on a frictionless plane inclined at angle θ = 30.7° is connected by a cord over a massless, frictionless pulley to a second block of mass m2 = 2.36 kg hanging vertically (Fig. 5-52). (a) What is the acceleration of the hanging block (choose ...

**Math**

Kris is starting a delivery business in Ottawa called Kris' Speedy Express. He charges $5, plus $1.50/kg to deliver a package throughout all of Ottawa including all outside communities. His competition, John's Same Day Deliveries charges $6 per delivery plus $1.00/kg. When is ...

**Algebra**

1) The following graphs shows the growth of the median home value in a particular region of the united states starting in 1996. The graphs states in 1996 and shows the trend through the year 2000; therefore x=0 represents the year 1996 and x=4 is 2000. x-axis (horizontal)= ...

**Physics**

A 2.6 N block is at rest on a horizontal surface. A 0.9 N upward force is applied to the block by means of attached vertical string. (a) What is the magnitude of the force of the block on the horizontal surface?

**Physics**

A 2.6 N block is at rest on a horizontal surface. A 0.9 N upward force is applied to the block by means of attached vertical string. (a) What is the magnitude of the force of the block on the horizontal surface?

**Physics**

Hillary kicks a ball so that it is in the air for 3.2 s. The ball lands down field 56 m from its starting point. a. Determine the x and y velocities of the ball.

**math urgent help!!!**

I need serious help with this problem. it is making me pukk my hair out!!! Yolanda and Yoko ran in a 100-yd dash. When Yolanda crossed the finish line, Yoko was ten yd behind her. The girls then repeated the race, with Yolanda starting 10 yd behing the starting line. If each ...

**Physics**

Use principles of force and kinematics to answer these: a. A 40 kg skater pushes on the 60 kg skater (initially at rest). As they collide, the 40 kg skater pushes on the 60 kg skater, applying a force 100 Newtons for 1.2 seconds. Find the velocity at which each of them ends up...

**physics**

Use principles of force and kinematics to answer these: a. A 40 kg skater pushes on the 60 kg skater (initially at rest). As they collide, the 40 kg skater pushes on the 60 kg skater, applying a force 100 Newtons for 1.2 seconds. Find the velocity at which each of them ends up...

**physics**

A block rests on a horizontal frictionless surface. A string is attached to the block, and is pulled with a force of 60.0 N at an angle θ above the horizontal. After the block is pulled through a distance of 2.00 m, its speed is 2.70 m/s, and 43.0 J of work has been done ...

**Physics**

A)A block rests on a horizontal frictionless surface. A string is attached to the block, and is pulled with a force of 60.0 N at an angle θ above the horizontal. After the block is pulled through a distance of 2.00 m, its speed is 2.70 m/s, and 43.0 J of work has been ...

**Physics**

A 15.0 gram bullet strikes and becomes embedded in a 1.24 kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.280, and the impact drives the block a distance of 11.0 m before it...

**physics**

A 46 g bullet strikes and becomes embedded in a 1.27 kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.28, and the impact drives the block a distance of 16.0 m before it comes...

**Chemistry**

Chromium is electroplated from an aqueous solution containing H2SO4 and H2CrO4. What current is required to deposit chromium at rate of 1.25g/min. 1.25g x 1mol/51.9961 = .0240mol Now I just don't know how to figure out the number of electrons to do the rest of the steps What ...

**Physics**

A small block slides along the inside of a hemispherical bowl of radius r = 41.4 cm. When the block is at an angle of θ = 62.3° above the lowest point, it is sliding down with a speed of v = 3.02 m/s and speeding up at a rate of 3.54 m/s2. Find the coefficient of kinetic...

**physics**

I have a question based off of the response to the question I posted below. A dragster and driver together have mass 918.8 kg. The dragster,starting from rest,attains a speed of 25.8 m/s in .53s . Find the average acceleration of the dragsters during this time interval. Answer...

**physics**

a roller coaster car moves 200 ft horizontally and then rises 135 ft at an angle of 30 degrees above the horizontal. It then travels 135 ft at an angle of 40 degrees downward. what is its displacement from its starting point? im not really sure what to do, I've drawn a graph ...

**Physics**

A block of mass M1positioned on a slope (at an angle ) is connected by means of an inextensible wire, of negligible mass, to another mass, m2, suspended from a frictionless pulley. The coefficients of static and dynamic friction between the slope and M1are 0.3 and 0.2...

**physics**

Mary weighs 519 N and she walks down a flight of stairs to a level 3.4 m below her starting point. What is the change in Mary’s potential energy? Answer in units of J.

**math**

Michael and mateo begin running around a circular track from the starting point at the same time. it takes Michael 48 seconds one lap around the track. it takes mateo 60 seconds to complete one lap around the track how many minutes does it take before the two boys will meet at...

**physics**

A block of mass M connected to an untstretched horizontal spring of spring constant k is hit by a bullet of mass m which has a velocity V just before the collision. The bullet stays in the block. The coefficient of friction between the block and surface is b. Explain how do ...

**physics**

in a shuffleboard game, the puck slides a total of 12 m before coming to rest. if the coefficient of friction is 0.21, what was the initial speed?

**physics**

A 4.3kg object moves across a floor with a velocity of + 8.2 m/s and slides to rest in 5.8 s. The net force producing this acceleration is:

**physics**

A solid ball and a hollow ball, each with a mass of 6 kg and radius of 0.1 m, start from rest and roll down a ramp of length 3 m at an incline of 31°. An ice cube of the same mass slides without friction down the same ramp. What is the speed of the ice cube at the bottom of ...

**physics**

A bullet A of mass 2kg travelling at 200m/s emblezes itself in a wooden block of mass 9kg moving in the opposite direction. At 20m/s. Calculate the velocity of the block when the bullet comes to rest inside the block. And what principle is used in the direction

**physics**

a dockworker applies a constant horizontal force of 80 N to a block of ice on a smooth horizontal floor. The friction force is negligible the block start from rest and move 11m in 5 sec what is it mass & if worker stop pushing at 5sec .How for does the block move in 5 ec

**Physics**

Please help!! I know how to work the problem to find velocities, but this one has me stumped! A 2.0kg block slides along a frictionless surface at 1.0m/s . A second block, sliding at a faster 4.4m/s , collides with the first from behind and sticks to it. The final velocity of ...

**Physics**

Sam pushes crates starting form rest across the floor of his classroom for 3 s with a net force as shown above. For each crate, rank the following from greatest to least: A 100N/30kg, B 75N/20kg C 50N/10kg 1. Impulse delivered 2. Change in momentum 3. Final speed 4. Momentum ...

**physics**

two people push in opposite directions on a block that sits atop a frictionless surface. The soles of their shoes are glued to the surface. if the block originally at rest moves to the right a distance of d. Describe qualitatively how much work is done by the person on the ...

**Physics**

A lumberjack (mass = 104 kg) is standing at rest on one end of a floating log (mass = 234 kg) that is also at rest. The lumberjack runs to the other end of the log, attaining a velocity of +3.18 m/s relative to the shore, and then hops onto an identical floating log that is ...

**Grade 9 Algebra Question 3 (LAST)**

PASCAL’S TRIANGLE For Exercises 5 and 6, use the following information. Blaise Pascal is known for a special triangular arrangement of numbers, calledPascal’s Triangle.. Each number insuccessive rows of the triangle is created by adding the two numbers in the row above the...

**physics**

A bullet of mass 12.4 g is fired into an initially stationary block and comes to rest in the block. The block, of mass 1.02 kg, is subject to no horizontal external forces during the collision with the bullet. After the collision, the block is observed to move at a speed of 4....

**physics**

A bullet of mass 11.2 g is fired into an initially stationary block and comes to rest in the block. The block, of mass 1.01 kg, is subject to no horizontal external forces during the collision with the bullet. After the collision, the block is observed to move at a speed of 4....

**College Physics**

A 6.76 kg block is attached to a spring with spring constant 36.9 N/m. While the block is sitting at rest, a student hits it with a hammer and almost instantaneously gives it a speed of 57 cm/s. What are The amplitude of the subsequent oscillations?

**physics**

In the figure, a 2.4 kg box of running shoes slides on a horizontal frictionless table and collides with a 1.4 kg box of ballet slippers initially at rest on the edge of the table, at height h = 0.75 m. The speed of the 2.4 kg box is 4.6 m/s just before the collision. If the ...

**Physics**

I was wondering if my answers are correct. Thanks in advance. 1. A boy pushes down on a car rolling horizontally down the road. The boy pushes down vertically with 10N of force as the car rolls 3.0m horizontally. What work is done? my answer: 30 N•m (or would it be -30N•m...

**physics**

A 506 g block is released from rest at height h0 above a vertical spring with spring constant k = 500 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 18.4 cm. How much work is done (a) by the block on the spring and (b...

**Dynamics**

The man slides the 100-kg crate across force of 200 N. If the crate was initially at rest, how far will the crate move before its speed is 1 m/s? The coefficient of kinetic friction between the crate and the floor is 0.18. The man is pulling the crate at a 20 degree angle.

**physics**

A block of mass m is initially at rest at the top of an inclined plane with a height = 4.4 m which makes and angle of θ = 17 degrees with respect to the horizontal. It is observed to be traveling at v = 0.2 m/s a distance d after the end of the inclined plane as shown. ...

**Physics**

A dragster and driver together have mass 900.7 kg. The dragster, starting from rest, attains a speed of 25.7 m/s in 0.54 s. 1. Find the average acceleration of the dragster during this time interval. Answer in units of m/s^2. 2. What is the size of the average force on the ...

**college physics**

Car A accelerates from rest at 2m/s2. It passes Car B, which is at rest. Thirty (30) seconds later, the latter follows with a constant speed of 10m/s. Determine the distance in order to overtake the other.

**SS**

1.) The Himalayas separate ______. a.) Pakistan and India b.) The Indian subcontinent from the rest of Asia. c.) Afghanistan from the rest of South Asia. d.)Northern and Southern Asia. B?

**physics**

Two identical small marbles A and B can be seen. A is at rest while B moves towards A at uniform velocity. The track is smooth towards left of P while it offers a resistance of 0.1 m/s2 towards its right. After some time, the marbles are seen at rest 25cms apart. After ...

**physics**

Let's say you're driving in your car, approaching a red light on the Camp Hill Bypass. A black Porsche is stopped at the light in the right lane, but there's no-one in the left lane, so you pull into the left lane. You're traveling at 40 km/hr, and when you're 15 meters from ...

**algebra**

A refrigerated truck leaves a rest stop traveling at a steady rate of 56 mi/h. A car leaves the same rest stop 1/4 hours later following the truck at a steady rate of 64 mi/h. How long after the truck leaves the rest stop will the ca overtake the truck?

**Physics**

a 2.5kg block initially at rest on horizontal surface. A horizontal force F of magnitude 6N and a vertical force P are the applied to the block. The coefficients of friction for the block and surface are Ms=0.4 and Mk=0.25.Determine the magnitude of the frictional force acting...

**Equation help**

A physics student stands at the top of a hill that has an elevation of 56 meters. he throws a rock and it goes up into the air and then falls back past him and lands on the ground below. The path of the rock can be modeled by the equation y=0.04x^2+1.3x+56 where x is the ...

**Physics**

A 0.40kg block is held against a compressed spring of stiffness 68.2N/m and compression 0.64m parallel to a 24 degree incline that is 1.27m long. The coefficient of kinetic friction between the block and the incline is 0.34. The external force holding the block against the...

**physics**

Two blocks of mass m1 = 1.0 kg and m2 = 2.5 kg are connected by a massless string. They are released from rest. The coefficent of kinetic friction between the upper block and the surface is 0.40. Calculate the speed of the blocks after they have moved a distance 72 cm. Assume ...

**physics**

A bullet with a mass 0.05kg is speeding toward a block of mass 10kg. the bullet is initially moving with a velocity of 200m/s while the block is initially at rest....The bullet collides with the block, sticking inside, and knocks the block horizontally of the edge of a cliff. ...

**mechanics**

You release a ball from rest attached to a string as shown in Figure A. The ball swings freely, and at the bottom of its circular path it strikes a stationary block. The block slides to the left with a speed of 4ms, and the ball bounces back to the right. To what maximum &#...

**physics**

(a) Suppose a hockey puck slides down a frictionless ramp with an acceleration of 5.60 m/s2. What angle does the ramp make with respect to the horizontal?

**math**

The head of an industrial machine moves in a straight line horizontally backwards and forwards from a central position. The movement can be modelled using the sine wave d = 80 sin ( pie t), where d is the horizontal distance (in cm) from the central starting position, and t is...

**physics**

Mary weighs 450 N and she walks down a flight of stairs to a level 4.50 m below her starting point. What is the change in Mary's potential energy? 1 J whats the PE formula? and setup?

**physic**

Two boxes are connected by by a massless string over a massless, frictionless pulley. Box 1 has a mass of m1 = 15.0 kg and is initially at rest at the bottom of a frictionless surface inclined at an angle θ = 30.0◦ above the horizontal. Box 2 has a mass of m2 = 10.0...

**physic**

Two boxes are connected by by a massless string over a massless, frictionless pulley. Box 1 has a mass of m1 = 15.0 kg and is initially at rest at the bottom of a frictionless surface inclined at an angle θ = 30.0◦ above the horizontal. Box 2 has a mass of m2 = 10.0...

**physics**

A block of mass 0.941 kg is kept at rest as i compresses a horizontal mass-less spring (K=87.5 N/m) by 9.91 cm. As the block is released, it travels 0.528 m on a rough horizontal surface before stopping. The acceleration of gravity is 9.8 m/s^2. Calculate the coefficient of ...

**engineering science**

An object weighing 60N rest on a slope forming an angle of 17.5 degrees with the horizontal. A force of 44N parallel to the sloping surface just moves the object upwards. Calculate the frictional force.

**Physics URGENT!!!**

Gayle runs at a speed of 9.00 m/s and dives on a sled, initially at rest on the top of a frictionless, snow-covered hill, that has a vertical drop of 20.0 m. After she has descended a vertical distance of 4.00 m, her brother, who is initially at rest, hops on her back, and ...

**science!**

1. A plane accelerated from a speed of 2.0 m/s at the rate of 3.0 m/s2 over a distance of 530 m. What is its speed after traveling this distance? 2. A jet plane must achieve a velocity of 71 m/s for takeoff. From rest and with a 1,000 m long runway, what must the acceleration ...

**Physics**

Two blocks, each with a mass = 0.168 kg, can slide without friction on a horizontal surface. Initially, block 1 is in motion with a speed = 1.28 m/s; block 2 is at rest. When block 1 collides with block 2, a spring bumper on block 1 is compressed. Maximum compression of the ...

**physics**

Two blocks, each with a mass m = 0.400 kg, can slide without friction on a horizontal surface. Initially, block 1 is in motion with a speed $v$ = 1.20 m/s; block 2 is at rest. When block 1 collides with block 2, a spring bumper on block 1 is compressed. Maximum compression of ...

**Physics**

A block of mass m=2 kg on a horizontal surface is connected to a spring connected to a wall (see figure). The spring has a spring constant k= 12 N/m. The static friction coefficient between the block and the surface is μs= 0.5 , and the kinetic friction coefficient is &#...

**Physics 12**

A large fake cookie sliding on a horizontal surface is attached to one end of a horizontal spring with spring constant k = 375 N/m; the other end of the spring is fixed in place. The cookie has a kinetic energy of 20.0 J as it passes through the position where the spring is ...

**physics**

A large fake cookie sliding on a horizontal surface is attached to one end of a horizontal spring with spring constant k = 375 N/m; the other end of the spring is fixed in place. The cookie has a kinetic energy of 20.0 J as it passes through the position where the spring is ...

**Physics**

A 3.0-kg cart is rolling along a frictionless, horizontal track towards a 1.2-kg cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a certain instant before the carts ...

**physics**

A 2.4-kg cart is rolling along a frictionless, horizontal track towards a 1.3-kg cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a certain instant before the carts ...

**physics**

A 2.9-kg cart is rolling along a frictionless, horizontal track towards a 1.5-kg cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a certain instant before the carts ...

**physics**

A 6.2 g piece of clay is propelled horizontally onto a block of wood with a mass of 18.4 g. The wood block is initially at rest on a 1.75 m tall post. After the collision the wood block will land 2.2 m from the base of the post. Find the initial speed of the clay.

**physics**

In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges

**Physics**

A block of mass 35kg is on a flat floor with a static friction coefficient of 0.36 and a kinetic friction coefficient of 0.29. A person attempts to slide the box from rest in a forward direction . Find the maximum frictional force experienced and the acceleration of the box ...

**physics**

A 450 g block is at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.670, and the coefficient of kinetic friction is 0.380. A force of magnitude P pushes the block forward and downward as shown in the figure below. Assume ...

**physics**

A light spring with force constant 3.00 N/m is compressed by 6.00 cm as it is held between a 0.350 kg block on the left and a 0.700 kg block on the right, both resting on a horizontal surface. The spring exerts a force on each block, tending to push them apart. The blocks are ...

**Physics**

A 45kg block slides down an incline that is angled at 41 degrees. If the coefficient of kinetic friction between the block and the incline is 0.45 what is the block's acceleration?

**Physics**

A 933 kg block is pushed on the slope of a 20 ◦ frictionless inclined plane to give it an initial speed of 50 cm/s along the slope when the block is 1.5 m from the bottom of the incline. The acceleration of gravity is 9.8 m/s 2 . 1.5 m 933 kg 20 ◦ What is the speed...

**physics**

A piece of iron block moves across a rough horizontal surface before coming to rest. The mass of the block is 1.8 kg, and its initial speed is 3.8 m/s. How much does the block's temperature increase, if it absorbs 69% of its initial kinetic energy as internal energy? The ...

**physics**

A 25.0 kg block is pulled 4.5 meters up a 20° rough incline by an applied force Fa = 200 N, directed up the ramp. The block starts from rest and has a final speed of 1.5 m/s. Find the following: a) The total work done on the block, Wtot =___ J b) The work done on the block by...

**Physics**

Ball A is attached to a string of length l=13.4 m and is released from rest. Ball B is released from rest and falls straight down. Which of the following statements for what happens at point P are correct, and which are incorrect? Explain your reasoning and state what is wrong...

**Physics**

A solid ball and a hollow ball, each with a mass of 2 kg and radius of 0.1 m, start from rest and roll down a ramp of length 3 m at an incline of 44°. An ice cube of the same mass slides without friction down the same ramp. What is the speed of the ice cube at the bottom of ...

**math-finance**

suppose you are offered two identical jobs: one paying a starting salary of $40,000 with yearly raises of $2,000 and one paying a starting salary of $36,000 with yearly raises of $25,000. Which job will pay more over a 10 year period? I=PRT = 40,000 x 0.05 x 10 = 20,000. S = ...

**physics**

A water slide can be thought of as being frictionless. Let's say a slider starts from rest and goes down a slide that is 30 m long and is set at a 25 degree incline. a) Determine the speed of the slider at the bottom of the slide. b) Explain why you don't need to know the mass...

**Physics**

A young woman named Kathy Kool buys a sports car that can accelerate at the rate of 4.77 m/s2. She decides to test the car by dragging with another speedster, Stan Speedy. Both start from rest, but experienced Stan leaves the starting line 1.04 s before Kathy. If Stan moves ...

**Physics**

A young woman named Kathy Kool buys a sports car that can accelerate at the rate of 4.53 m/s2. She decides to test the car by dragging with another speedster, Stan Speedy. Both start from rest, but experienced Stan leaves the starting line 1.01 s before Kathy. If Stan moves ...

**Physics**

Hi I have a question in Physics A block with mass 50kg is held on a slope. Ù friction coefficient = 0.35 between the plane and the block .. Planets angle v with the horizontal is 25 degrees. How far will the block slide down the plane in 5 seconds after it is released (in ...

**physics**

there is a massless rope that is pulled over a frictionless pulley that is suspended high above the ground one end of the rope is tied to a heavy block with a mass of 483 kg the free end is climbed by a person with a mass of 102 kg who starts from rest. If during the time of ...

**Physics**

A solid sphere rolls without slipping from rest down a plane at 4.00m long inclined at an angle of 42 degrees with respect to the horizontal as shown in the figure below. Determine the speed at the bottom of the incline.

**Applied Calculus**

If an object is launched straight up into the air from a starting height of h_{0} feet, then the height of the object after t seconds is approximately h=-16t^2+v_{0}t+h_{0} feet, where v_{0} is the initial velocity of the object. Find the starting height and initial velocity ...

**Applied Calculus**

If an object is launched straight up into the air from a starting height of h_{0} feet, then the height of the object after t seconds is approximately h=-16t^2+v_{0}t+h_{0} feet, where v_{0} is the initial velocity of the object. Find the starting height and initial velocity ...

**physics**

In the following figure m_1 = 20.0kg kg and á alpha = 50.9 ∘ ^\circ. The coefficient of kinetic friction between the block and the incline is ì k = 0.40 What must be the mass m 2 of the hanging block if it is to descend 9.00m m in the first 3.00s s after the system is ...

**college physics**

a bullet of mass 8g is fired into a block of mass 260g that is initially at rest at the edge of a table of height 1m the bullet remains in the block and after the impact the block land d=2.20m for the bottom of the table. determine the speed of the bullet

**PHYSICS**

A block with mass m1 = 9.0 kg is on an incline with an angle θ = 32.0° with respect to the horizontal. For the first question there is no friction, but for the rest of this problem the coefficients of friction are: μk = 0.28 and μs = 0.308. To keep the mass ...

**PHYSICSS HELP**

3)-A 9-kg block is held by a pulley system shown in fig. What force must the person exert in the following cases: a) to hold the block at rest. b) to lower it at 2m/s. c) to raise it with an acceleration of 0.5 m/s2? Ignore the mass of small pulley.

**PHYSICS HELP**

3)-A 9-kg block is held by a pulley system shown in fig. What force must the person exert in the following cases: a) to hold the block at rest. b) to lower it at 2m/s. c) to raise it with an acceleration of 0.5 m/s2? Ignore the mass of small pulley.