# Homework Help: Science: Physics

## Recent Homework Questions About Physics

**Physics**

Assume a person expends mechanical energy at a rate of 450 W. If they were 15% efficient, what would be the rate at which he/she generates waste heat energy?

**Physics**

An adult dolphin weighs around 1460 N. How fast must he be moving as he leaves the water vertically in order to jump to a height of 2.90 m? Ignore air resistance.

**physics**

A small disk of radius r is glued onto a large disk of radius R that is mounted on a fixed axle through its center. the combined moment of inertia of the disks is I. A string is wrapped around the edge of the small disk and a box of mass m is tied to the end of the string. the...

**Physics**

passenger must experience no greater than 10 times the magnitude of the acceleration due to gravity as the spring cushions their fall & brings the elevator to rest. Calculate the spring constant assume mass of elevator and passenger is 'M' kg. what is the spring constant so ...

**physics**

Two crates rest on top of one another.There is a crate of mass 4.62 kg on top of another crate of mass 2.19 kg. The coefficient of friction between the lower crate and the floor is μk = 0.440 and the coefficient of static friction between the two crates is μs = 0.870. If the...

**physics**

A ball is thrown horizontally off a building that is 30 m high with an initial velocity of 3 m/s.if an identical ball is thrown again horizontally from the same height with 6 m/s, what happens to the flight time? I have to use the guess method. Givens Unknown Equation ...

**Physics**

A mass is tied to a 1 m string. The string is attached to a point on a horizontal frictionless surface and the mass is set into circular motion. The string will break if tension becomes larger than 10 N. The maximum kinetic energy that the mass can achieve before the string ...

**physics**

A body moving with a velocity of 3m/s is brought to rest by a constant force after travelling 15m, calculate the retardation.

**Physics**

A)A 100kg person is riding a 10kg bicycle up a 25degree hill. The hill is long and the coefficient of static friction is 0.9. How much force does the person have to apply in order for her to ride 10m up the hill at constant velocity? B) If the person now starts from rest from ...

**Physics Urgent!**

Please help! This is due in three hours and I don't know how to do these! 1.A block accelerates at 3.1 m/s2 down a plane inclined at an angle 24.0◦. Find μk between the block and the inclined plane. The acceleration of gravity is 9.81 m/s2 . 2.Two blocks connected by a ...

**Physics**

If a particle takes two revolution in one sec & it took five revolution .Find angular velocity of particle.

**physics -damon help**

An ac source of 50v,100÷πHz is connected in series with an inductor of inductance L ad a resistor of resistance R.the current in the circuit is 2A ad p.d. across L and R are 30v ad 40v respectively 1) calc d average power dissipated 2) calc d power factor in the circuit

**Physics**

1. A 1200 kg car moves along a horizontal road at speed v0 = 20.1 m/s. The road is wet, so the static friction coefficient between the tires and the road is only μs = 0.189 and the kinetic friction coefficient is even lower, μk = 0.1323. The acceleration of gravity is 9.8 m/...

**Physics**

1. A snowboarder of mass 60 kg is at rest on the top of a sand dune. The coefficients of static and kinetic friction are 0.55 and 0.4675, respectively. 60 kg μk = 0.4675 μs = 0.55 What is the angle the incline must exceed so that the snowboarder starts sliding? The ...

**Physics**

A 1200kg car rounds a curve of radius of 50m with a speed of 80km/hr. What is the coefficient of friction if the car is just about to skid off the road? I got: ac= 9.88m/s2 Fc= 11851N I also know Ff=uFN but have no idea how to figure this out. Thx.

**Physics**

A rod is lying on the top of a table. One end of the rod is hinged to the table so that the rod can rotate freely on the tabletop. Two forces, both parallel to the tabletop, act on the rod at the same place. One force is directed perpendicular to the rod and has a magnitude of...

**physics**

A 3 kg block (block A) is released from rest at the top of a 20 m long frictionless ramp that is 5 m high. At the same time, an identical block (block B) is released next to the ramp so that it drops straight down the same 5 m. Find the values for each of the following for the...

**Physics**

A 3.2 Kg box is pressed up against a wall by a person’s arm that makes a 35-degree angle with the wall. The box slides down the wall with a uniform speed. There is a coefficient of friction of 0.45 between the box and the wall. A. What is the magnitude the force that the ...

**Physics**

QUESTION: In the figure provided, a 2.83 kg textbook is connected by a string to a 0.970 kg cup. The textbook is pushed up a slope of 34.7° with an initial speed of 2.81 m/s. If the coefficients of friction are uk = 0.370 and Îus = 0.760 with the surface, how far will the ...

**Physics**

A 1200 kg car moves along a horizontal road at speed v0 = 20.1 m/s. The road is wet, so the static friction coefficient between the tires and the road is only μs = 0.189 and the kinetic friction coefficient is even lower, μk = 0.1323. The acceleration of gravity is 9.8 m/s2...

**Physics**

a) Rain drops hitting the side window of a car in motion often leave diagonal streaks if there is no wind. Why? b) For a certain projectile, the horizontal range is twice in magnitude of the maximum height attained by it. Find its angle of projection.

**Physics**

Two workers pull horizontally on a heavy box, but one pulls twice as hard as the other. The larger pull is directed at 25 degree west of north and the resultant of these two pulls is 350 netwon directly northward. Use vector components to find the magnitude of each of these ...

**Physics**

An automobile is travelling west. Can it have velocity towards west and at the same time can it have acceleration towards the east? Under what circumstances.

**physics**

A 1200 kg car traveling north at 14 m/s is rear ended by a 2000 kg truck traveling at 25 m/s. If the truck and car lock bumpers and stick together, what is their speed immediately after the collision?

**Physics Urgent!**

A snowboarder of mass 60 kg is at rest on the top of a sand dune. The coefficients of static and kinetic friction are 0.55 and 0.4675, respectively. 60 kg μk = 0.4675 μs = 0.55 What is the angle the incline must exceed so that the snowboarder starts sliding? The ...

**Physics**

At what altitude above the Earth's surface is the gravitational field strength equal to g/7? .981 = -(1.0003322(6,371/6,371+h))^2)

**Physics**

1.A block accelerates at 3.1 m/s2 down a plane inclined at an angle 24.0◦. Find μk between the block and the in- clined plane. The acceleration of gravity is 9.81 m/s2 . 2.A 1200 kg car moves along a horizontal road at speed v0 = 20.1 m/s. The road is wet, so the static ...

**Physics**

1.A student moves a box of books down the hall by pulling on a rope attached to the box. The student pulls with a force of 181 N at an angle of 20.8◦ above the horizontal. The box has a mass of 40.3 kg, and μk between the box and the floor is 0.29. The acceleration of ...

**Physics Urgent!**

1.You are driving at the speed of 28.7 m/s (64.2138 mph) when suddenly the car in front of you (previously traveling at the same speed) brakes. Considering an average human reaction, you press the brakes 0.427 s later. Assume that the brakes on both cars are fully engaged and ...

**Physics**

A hockey puck is hit on a frozen lake and starts moving with a speed of 12.1 m/s. Four seconds later, its speed is 6.7 m/s. What is its average acceleration? The ac- celeration of gravity is 9.8 m/s2 . Answer in units of m/s2. What is the average value of the coefficient of ...

**physics**

A 3 kg block is released from rest at the top of a 20 m long frictionless ramp that is 5 m high. Find the values for the block just before it reaches ground level. (a) gravitational potential energy ----J (b) kinetic energy ----J (c) speed -----m/s (d) momentum ------kg·m/s

**physics**

Two crates rest on top of one another.There is a crate of mass 4.62 kg on top of another crate of mass 2.19 kg. The coefficient of friction between the lower crate and the floor is μk = 0.440 and the coefficient of static friction between the two crates is μs = 0.870. If the...

**physics**

Two buses leave a bus station and travel in opposite direction from the same standing point.if the speed of one is twice the other and they are 240km apart at the end of one hour. What is the speed of each km

**Physics**

calculate the magnitude of electrostatic force on a charge placed at a vertex of a triangular pyramid (4 vertices, 4 faces), if 4 equal point charges are placed at all four vertices of pyramid of side'a.

**Physics**

What does it mean if a motor is described as “One Horsepower”?

**Physics**

An electric train leaves a station starting from rest and attains a speed of 72km/hr in 10 second. It travels at that speed for 120 seconds. Then it undergoes uniform retardation for 20 seconds to come to halt at the next station calculate : a) distance between the train ...

**Physics 1**

A 2.5 meter long string vibrates as a 100 hertz standing waves with nodes at 1.5 meters and 1.0 meters from one end of the string and at no points between the two strings, which harmonic is this? and what is the strings fundamental frequency?

**physics**

What is the rotational speed of the hour hand on a clock? -----rev/s

**Advanced Physics**

What is the displacement for the following vectors? A vector moving 45 degrees northeast at a velocity of 3m/s and turns 30 degrees southeast

**Physics 1**

a 12.5 m long string vibrates as 100 hertz standing wave with nodes at 1.0m and 1.5m from one end of the string and at no points in between the two. Which harmonic is this? What is the string's fundamental frequency?

**physics**

An ideal gas has the following initial conditions: Vi = 490 cm3, Pi = 5 atm, and Ti = 100°C. What is its final temperature if the pressure is reduced to 1 atm and the volume expands to 1000 cm3? _____°C

**physics**

The pressure in each of your car tires is 2.10 105 Pa. The mass of your car is 1550 kg. Assuming that each of your tires bears one-quarter of the total load, what is the contact area of each tire with the road? ______ m2

**physics**

Given that the carbon atom has a mass of 12 amu, how many carbon atoms are there in a diamond with a mass of 8 g? ....atoms

**physics**

A ham sandwich consists of one slice of ham (9 grams) and two slices of bread (25 grams each). You have 1 kg of ham and 1.2 kg of bread. You make as many sandwiches as you can. How many sandwiches did you make? 1) How many sandwiches? 2) What is the mass of the sandwiches? g 3...

**physics**

What is the rotational speed of the hour hand on a clock? -----rev/s

**physics**

A variable-speed drill, initially turning at 150 rpm, speeds up to 1300 rpm in a time interval of 1.0 s. What is its average rotational acceleration? ----rpm/s2

**physics**

Two crates rest on top of one another.There is a crate of mass 4.62 kg on top of another crate of mass 2.19 kg. The coefficient of friction between the lower crate and the floor is μk = 0.440 and the coefficient of static friction between the two crates is μs = 0.870. If the...

**physics**

You are driving at the speed of 34.3 m/s (76.7433 mph) when suddenly the car in front of you (previously traveling at the same speed) brakes. Considering an average human reaction, you press the brakes 0.429 s later. Assume that the brakes on both cars are fully engaged and ...

**Physics**

The work function for a particular metal is 2.18 eV. What is the kinetic energy in eV of photoelectrons ejected when 410 nm violet light falls on this metal?

**physics**

A can of Coke moving 15.6 m/s toward the right(the positive direction) collides with a can of Pepsi moving 3.21 m/s toward the left, and both cans are badly crunched. If the final velocity of the can of Coke is 2.48 m/s still toward the right, then what is the final velocity ...

**Physics**

Calculate the speed a spherical rain drop would achieve falling from 5.00 km (a) in the absence of air drag (b) with air drag. Take the size across of the drop to be 4 mm, the density to be 1.00×103 kg/m3 , and the surface area to be πr2

**physics**

bobpursley pleas put more details on how you got your answers to my previous physics questions... thanks

**Physics**

A ballistic pendulum is a device for measuring bullet speeds. One of the simplest versions consists of a block of wood hanging from two long cords. (Two cords are used so that the bottom face of the block remains parallel to the floor as the block swings upward.) A 0.013-kg ...

**Physics**

A 0.45-kg soccer ball is kicked at an angle θ above the ground with initial speed vi. Determine the height of the ball as a function of the horizontal distance d it travels down the field.

**physics**

A group of construction workers are building a house and want to lower down an excess bundle of 1420 kg bricks to ground. They tie one end of a rope to the bundle of bricks, loop it through a pulley, and tie the other end of the rope to a toolbox. If the coefficient of kinetic...

**physics**

A 1070 kg hybrid car pushes a 2140 kg Jeep that has died on railroad tracks. If the wheels of the hybrid car push against the ground with 5890 N of force, what is the magnitude of the force between the hybrid car and the Jeep? Assume there is no rolling friction.

**Physics**

A car starts from rest and attains a velocity of 40 metres per second in 20 seconds. it maintains this velocity for 30 seconds and then comes to rest in 25 seconds. 1. sketch the velocity time graph for the motion. 2. Calculate the acceleration of the body. 3. Calculate the ...

**PHYSICS**

what is the angle velocity of an object in a horizontal circular part with radius 1.5 with a constant speed of 12/s

**physics**

Movers are looking to lower a cabinet out of an open window to a mattress on the ground below. One end of a rope is tied to a 193 kg dresser, looped through a pulley, and the other end of the rope is tied to a cabinet. If the coefficient of kinetic friction between the dresser...

**physics**

A car of mass m is going around a circular turn of radius R, which is banked at an angle Î² with respect to the ground. Assume there is friction between the wheels and the road. Let Î¼s be the coefficient of static friction and g the magnitude of the gravitational ...

**Physics**

A body A of a mass 0.16 kg exerts a force of 6.2x10^-10 N on a body B when the distance between their centers is 0.37 meters. What is the mass of body B?

**physics**

A block and tackle has a velocity ratio of 4 and it is used to vertically raise a load of mass 50kg.if the effciency is 80%,determine the minimum effort reguired to raise the load.

**Physics**

A block of metal, mass m kg, is placed on a horizontal frictionless surface. It is then acted upon by a force equal to half its weight in a direction parallel to the surface. What's the acceleration it experience?

**Physics**

A man pushes a lawn mower on a level lawn with a force of 203 N. If 26% of this force is directed downward, how much work is done by the man in pushing the mower 7.0 m?

**Physics**

Hello, I need some help with this physics problem. This was the only one I couldn't solve, and the teacher wouldn't help me because she wanted me to figure it out for myself, just like everyone else tried. (Although no one did) Here is the question: Type in imgur dot com slash...

**Physics**

Suppose that a cars x-acceleration during a certain time period is given by the function a(t) = -bt. If the cars x-velocity at t=0 is 32m/s, and b=1m/s^2, how long will it take the car to come to rest.

**Physics**

What is the terminal speed for an 77 kg skier going down a 45 âˆ˜ snow-covered slope on wooden skis Î¼k= 0.060? Assume that the skier is 1.8 m tall and 0.40 m wide. Assume the skier's drag coefficient is 0.80. Express your answer using two significant figures with the ...

**URGENT ANY PhYSIcs teacher help thouroighly pls**

The coefficiant of friction between rubber tires and wet pavement is 0.5. Breaks are alllied to a 750kg car, intitally travelling at 30 m/s and the car skids to a stop. What is the magnitude and direction of the acceleration. Ik the magnitude and i kinda get how to do the ...

**Physics 11 damon pls URGENT!**

The coefficiant of friction between rubber tires and wet pavement is 0.5, and the breaks are applied to 750kg car, intitally travelling at 30m/s and the car skids to a stop. What is size and difection of the acceleration. How do i find acceleration of the vehicle

**Physics 11 steve, bob,physics expert pls URGENT!!**

Coefficiant of friction between rubber tires and wet pavement is 0.50. brakes are applied to a 750kg car, intitally travelling at 30m/s and the car skids to a stop. What is the size and direction of the acceleration of the car.

**physics**

(1) A uniform meter rod 4ON has a piece of weight of 2ON attached to one of its end. What is the center of gravity of the system from the weight end? (2) two bodies X and Y start from rest and move with uniform acceleration of a and 4a respectively. If the bodies cover the ...

**physics**

A 84.0 kg person is being pulled away from a burning building as shown in the figure below.

**Physics**

When the Sun is directly overhead, a hawk dives toward the ground at a speed of 6.09 m/s. If the direction of his motion is at an angle of 78.6 â—¦ below the horizontal, calculate the speed of his shadow along the ground. Answer in units of m/s

**physics**

A car travels at a constant speed around a circular track whose radius is 2.87 km. The car goes once around the track in 332 s. What is the magnitude of the centripetal acceleration of the car?

**Physics**

A girl delivering newspapers travels 3 blocks west, 8 blocks north, then 5 blocks east. 1) What is the magnitude of her resultant displacement? Answer in units of blocks. 2) Find the direction (measured from due east, with counterclockwise positive) of her displacement. Answer...

**Physics**

You buy a plastic dart gun, and being a clever physics student you decide to do a quick calculation to find its maximum horizontal range. You shoot the gun straight up, and it takes 36.761s for the dart to land back at the barrel. What is the maximum horizontal range of your gun?

**physics**

a uniform pole 7m long and weighing 10kg suppoted by a boy 2m from one end man3 from other end

**Physics**

A spring is attached to the top of a table. The spring has a spring constant of 500.0 N/m. The spring is initially compressed by 1.50 m by a baseball (0.145 kg). How much energy is present in the system from the compression? After release, what is the velocity at which the ...

**Physics**

a spring hanging from the ceiling. The spring constant present is 200N/m. If a mass of 50 kg is attached, how far does the spring stretch?

**PHYSICS**

A person sits on a frictionless stool that is free to rotate but is initally at rest. The person holding a bicycle wheel (I = 3 kg*m2) that is 8 rev/s in the clockwise direction as viewed from above, and the moment of inertia of the person-sheel-stool system is 9 kg*m2. 1. ...

**physics**

If the gravitational force F is given by F=GM1M2Ãƒ·rÃƒâ€”r.derive the dimensions of the universal constant of the gravitational G

**Physics - Circular motion**

A domesticated pig places a 100g rubber puck on a turntable. The turntable is set at a rate of 78rpm,and the pig knows the coefficient of static friction is 0.37 between the puck and turntable surface. A) How far out from the center of the turntable can the puck be places ...

**Physics - circular motion**

You approach a slight bump in the road on the highway in a car. The bump carries you into a circular (convex) vertical arc of radius 39m. A) choosing two different cars ( it is for you to choose 2 particular models, providing the mass of each), at what maximum speed can you ...

**physics**

The large quadriceps muscle in the upper leg terminates at its lower end in a tendon attached to the upper end of the tibia (see figure (a)). The forces on the lower leg when the leg is extended are modeled as in figure (b), where vector T is the force of tension in the tendon...

**Physics**

a truck travels up a hill with a 12% incline. the truck has a constnt speed of 22m/s. what is the horizontal componet of the reucks velocity

**PHYsics**

A sprinter of mass 70.7 kg runs at a constant speed of 10.5 m/s in a straight line. Find the extra force the sprinter must exert on the ground to round a curve of radius 10.6 m.

**Physics**

2. The average atmospheric pressure at sea level is approximately 101 000 Pa. If the density of air at 0◦C is approximately 1.3 kg , how high does the atmosphere extend?

**Physics**

A long, straight wire with a circular cross section of radius R carries a current I. Assume that the current density is not constant across the cross section of the wire, but rather varies as J=αr, where α is a constant. A) By the requirement that J integrated over ...

**Physics**

A piece of copper ball of mass 30grams at 150 degree celcius is placed in a copper calorimeter of mass 70gams containing 60grams of waterof copper 40degree celcius if the final ofthe mixture is 50degree celcius calculate the specific heat capacity of copper (specific heat ...

**Physics**

A student holds a bike wheel and starts it spinning with an initial angular speed of 7.0 rotations per second. The wheel is subject to some friction, so it gradually slows down. In the 10-s period following the inital spin, the bike wheel undergoes 60.0 complete rotations. ...

**Physics**

A uniform disk of radius 0.485 m and unknown mass is constrained to rotate about a perpendicular axis through its center. A ring with same mass as the disk\'s is attached around the disk\'s rim. A tangential force of 0.247 N applied at the rim causes an angular acceleration of...

**Physics**

A flywheel in the form of a uniformly thick disk of radius 1.48 m, has a mass of 43.6 kg and spins counterclockwise at 303 rpm. Calculate the constant torque required to stop it in 2.50 min.

**Physics**

Six dogs pull a two-person sled with a total mass of 280 kg. The coefficient of kinetic friction between the sled and the snow is 0.080. The sled accelerates at 0.65 m/s2 until it reaches a cruising speed of 15 km/h. What is the team's maximum power output during the ...

**Physics**

A pile driver lifts a 450 kg weight and then lets it fall onto the end of a steel pipe that needs to be driven into the ground. A fall of 1.5 m drives the pipe in 45 cm. What is the average force exerted on the pipe?

**Physics**

A concave, spherical mirror and a thin, converging lens are both measured in air (n=1.0) to have the same focal length, ff. Both the mirror and the lens are then placed under water (n=1.33) and their focal lengths are measured again. For both the mirror and the lens state ...

**Physics 11 urgent Steve, bob, damon pls**

A 30 kg student pushes a 20kg box on frictionless surface. If student accelerates at 0.8m/s^2(N),what is acceleration of bix. now why does the box acceerate towards south, if it is being pushed north should it not move north.

**physics**

A uniform ladder of length 20.0m and weight 750 N is propped up against a smooth vertical wall with its lower end on a rough horizontal surface. The coefficient of friction between the ladder and this horizontal surface is 0.40. (b) Work out and add the numerical values of ...

**Physics**

A soccer play kicks the ball toward a goal that is 29m in front of him. The ball leaves his foot at a speed of 19m/s and at an angle of 32degrees above the ground. Find the speed of the ball when the goalie catches it in front of the net. my work: vxi=16.1 vxf=16.1 ax=0

**university physics**

An object at rest explodes into three fragments. The figure shows the momentum vectors of two of the fragments: vector P1 is directed along the px axis and has a magnitude of 74.0 kg m/s. vector P2 is at an angle of 300.° measured counterclockwise from the positive px axis ...

**Physics 11 steve or any physics teacher helpURGENT**

A 30kg student pushes a 20kg box on a frictionless surface. If student accelerates at 0.80 m/s^2, what is acceleration of the box. My question is why does the box accelerate in opposite direction of the boy, and how does the frictionless surface affect this question?