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September 1, 2014

September 1, 2014

**Recent Homework Questions About Physics**

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**physics**

Joe pushes horizontally on a heavy box across a rough surface at constant speed. Which one of the following statements concerning this situation is false? If Joe stops pushing on the box, the box will stop sliding eventually. If Joe doubles his force on the box, the speed of ...
*Sunday, June 8, 2014 at 7:43am*

**Physics**

A ball is sitting in a child's wagon and a child is holding the wagon's handle. The ball then rolls to the back of the wagon without anyone touching the ball directly. Which of the following statements according to Newton's first law of motion could describe the ...
*Sunday, June 8, 2014 at 7:41am*

**Physics**

A train on a mountain railway is carrying 200 people of average mass 70kg up a slope at an angle of 30° to the horizontal and at a speed of 6.0 m s–1. The train itself has a mass of 80 000 kg. The percentage of the power from the engine which is used to raise the ...
*Sunday, June 8, 2014 at 3:11am*

**physics**

prove that for finite length current element ?H = I/2πr(sinα2 - sinα1)aφ
*Sunday, June 8, 2014 at 2:54am*

**physics**

Three identical point charges A, B, and C are located in the shape of an equilateral triangle with sides of length 15 cm. What is the net force on B if each charge has a magnitude of −5.0 × 10−3 C?
*Sunday, June 8, 2014 at 1:42am*

**physics**

Energy & Momentum Calculations Assessment Answer the following questions. A 1.0 kg puck sliding at 15 m/s along some horizontal frictionless ice strikes and compresses a horizontal spring attached to one end of the ice rink. If the spring has a constant of 35 N/m, what is the ...
*Sunday, June 8, 2014 at 1:18am*

**Physics**

Can someone explain the magnitude and direction of the acceleration of a ball moving upward, downward,and at the highest point? a=g
*Sunday, June 8, 2014 at 1:14am*

**physics**

Calculate the mass of the star using the fact that the period of the planet is 3.07 × 107 s and its distance from the star is 1.26×1011 m. Answer in units of kg
*Saturday, June 7, 2014 at 11:57pm*

**Physics**

June stands on the roof of the house which is 22.8 m high and she throws the ball at an initial speed of 4.90 m/s downward at Ben who is 1.80m tall. a) With what speed does she hit her target's head and b) how much time was it in the air? Displacement= 21 m. -Place ...
*Saturday, June 7, 2014 at 10:34pm*

**physics**

Which one of these statements concerning elastic collisions is FALSE? Select one: a. The two objects remain together after collision b. The kinetic energy is conserved c. The momentum is conserved
*Saturday, June 7, 2014 at 10:06pm*

**physics**

An electron reaches a speed of 3.0 × 107 m/s when released beside the negative plate within a parallel plate accelerator with a gap of 15.0 cm. If the mass of an electron is 9.11 × 10−31 kg, what is the potential difference between the plates?
*Saturday, June 7, 2014 at 10:05pm*

**physics**

You shoot a 57 gram dart vertically upwards from a catapult with a spring constant of 379 N/m. The catapult is initially stretched from the equilibrium point by 30 cm. What is the height above the starting point reached by the dart? Ignore air resistance and give your answer ...
*Saturday, June 7, 2014 at 10:04pm*

**physics**

Which one of these statements regarding non-conservative forces is FALSE? Select one: a. A non-conservative force cannot have a potential energy defined for it. b. The work done by a non-conservative force may be either positive or negative depending on the direction of motion...
*Saturday, June 7, 2014 at 10:03pm*

**college physics**

A horizontal spring with a spring constant k = 322 N/m is uncompressed from a length of 1.4 cm back to its unstretched length. Calculate the change in potential energy in Joules to 2 s.f.
*Saturday, June 7, 2014 at 6:43pm*

**college physics**

You shoot a 57 gram dart vertically upwards from a catapult with a spring constant of 379 N/m. The catapult is initially stretched from the equilibrium point by 30 cm. What is the height above the starting point reached by the dart? Ignore air resistance and give your answer ...
*Saturday, June 7, 2014 at 6:42pm*

**physics**

Which one of these statements concerning elastic collisions is FALSE? Select one: a. The two objects remain together after collision b. The kinetic energy is conserved c. The momentum is conserved
*Saturday, June 7, 2014 at 6:41pm*

**physics**

Which one of these statements regarding non-conservative forces is FALSE? Select one: a. A non-conservative force cannot have a potential energy defined for it. b. The work done by a non-conservative force may be either positive or negative depending on the direction of motion...
*Saturday, June 7, 2014 at 6:38pm*

**Physics**

An engine of the orbital maneuvering system (OMS) on a space shuttle exerts a force of for 3.90 s, exhausting a negligible mass of fuel relative to the 95,000-kg mass of the shuttle. (a) What is the impulse of the force for this 3.90 s? (b) What is the shuttle’s change in...
*Saturday, June 7, 2014 at 5:57pm*

**physics**

The charge on two pith balls can be calculated by knowing their masses and observing the angle of separation between the balls. If both balls are equally charged and they are suspended by strings that are 1.0 m long, calculate that charge. (mass for both balls = 0.003kg) angle...
*Saturday, June 7, 2014 at 5:09pm*

**Physics**

Frank is traveling the posted speed limit of 36 mi/hr in a school zone. A deer darts out between two cars. He instantly hits the brakes and the car decelerates at a rate of 5.0 m/s^2. a) how much stopping distance will he require in (meters)? b) If he was going twice the ...
*Saturday, June 7, 2014 at 5:05pm*

**physics**

Using that velocity, and the information from above, compare the total momentum just before the collision with the total momentum after the collision. (again let the masses of the balls be m) , it is a lab question , i was just wondering what formula to use for the momentum
*Saturday, June 7, 2014 at 4:41pm*

**Physics**

Explanation of twin paradox in regards to special relativity theory.
*Saturday, June 7, 2014 at 2:52am*

**physics**

two positive points charges of 15c and 13c are placed 12cm apart . find the work done in bringing the two charges 4cm closer.
*Saturday, June 7, 2014 at 2:27am*

**physics**

a train 100m long is to cross a river bridge of length 800m. what time it take to cross the bridge ?velocity of train is 36km/h.
*Saturday, June 7, 2014 at 2:20am*

**physics**

Using the data from Step #3 and the velocity found above, compare the gravitational potential energy of the ball at the top of the incline, with the kinetic energy of the ball just before it leaves the table. (you do not need to know the mass, just let it equal m). Is ...
*Friday, June 6, 2014 at 9:02pm*

**physics**

Calculate the average velocity for a remote controlled vehicle that starts with a speed of 1.0 m/s [forward] and then accelerates at 0.08 m/s2 [backward] for 4.0 s.
*Friday, June 6, 2014 at 6:39pm*

**physics**

How much additional energy is needed to fire a 7.2 × 10^2 kg weather monitor on the earth’s surface to a height of 120 km above the earth? (rE = 6.38 × 10^6 m, ME = 5.98 × 10^24 kg) Assume that the weather monitor rises to that height, stops, and falls ...
*Friday, June 6, 2014 at 2:59pm*

**physics**

The gravitational field strength of an unknown planet is 15.5 N/kg on its surface. Calculate the value of g if the planets mass and radius were both doubled.
*Friday, June 6, 2014 at 2:39pm*

**physics**

A mother pulls her two children on a sled through the snow along a flat street. How much work is done if she pulls her children 100 feet with a constant force of 40 pounds at an angle of 28°?
*Friday, June 6, 2014 at 12:19pm*

**physics**

A heat engine has a hot reservoir of 680°C and a cold reservoir of 220°C. What is the efficiency of the engine?
*Friday, June 6, 2014 at 10:18am*

**physics**

Calculate the mass of Jupiter knowing that a person who weighs 490 N on the earth's surface would weight 1293 N on the surface of that planet. Jupiter has a radius of 7.15 × 10^7 m.
*Thursday, June 5, 2014 at 10:43pm*

**Physics **

A horizontal spring with spring constant 110N/m is compressed 16cm and used to launch a 2.8kg box across a frictionless, horizontal surface. After the box travels some distance, the surface becomes rough. The coefficient of kinetic friction of the box on the surface is 0.15. ...
*Thursday, June 5, 2014 at 10:01pm*

**physics**

Calculate the mass of Jupiter knowing that a person who weighs 490 N on the earth's surface would weight 1293 N on the surface of that planet. Jupiter has a radius of 7.15 × 107 m.
*Thursday, June 5, 2014 at 9:53pm*

**Physics **

Can anyone figure this out? A cable with 25.0N of tension pulls straight up on a 1.10kg block that is initially at rest. What is the block's speed after being lifted 2.30m ? Solve this problem using work and energy.
*Thursday, June 5, 2014 at 7:19pm*

**Physics **

A system gains 473J of kinetic energy while losing 271J of potential energy. The thermal energy increases by 127J . Use an energy bar chart of this process to find the external work Wext.
*Thursday, June 5, 2014 at 7:18pm*

**Physics **

How much work is done by the force F⃗ =(− 3.0 i^− 7.6 j^)N on a particle that moves through displacement Δr⃗ = 3.6 i^−2.0j^m?
*Thursday, June 5, 2014 at 7:05pm*

**physics**

What is the minimum speed required to simulate artificial gravity?
*Thursday, June 5, 2014 at 5:00pm*

**physics**

Determine the final velocity of a medicine ball that is dropped from a height of 7.00 meters. (assume air resistance is negligible) I don't understand how to solve this with only change in x. I imagine I am supposed to assume initial velocity is 0 m/s, but, even if that is...
*Thursday, June 5, 2014 at 3:21pm*

**mechanical physics**

1)Answer 3.2rad/sec 2)Answer 2.2rad/sec
*Thursday, June 5, 2014 at 7:15am*

**Physics **

A person is initially 8 m from a point sound source which emits energy uniformly in all direction at a constant rate. If the intensity of the source is to be halved but the sound is to be as loud as before, what distance should the person be from the source? Ans: 4 square root...
*Thursday, June 5, 2014 at 4:24am*

**Physics**

Help on these few questions please? :( I'm so confused. No need for a direct answer if you don't wanna give it but I just need some explaining. thank you. points) Score A ball is thrown horizontally from a platform so that the initial height of the ball is 6.0 m above ...
*Thursday, June 5, 2014 at 2:43am*

**Physics **

The displacement, force, velocity, and acceleration vectors’ components are given. Calculate the magnitude and direction of each vector. (a) x = +15.0 cm, y = -12.3 cm. I am completely lost.
*Wednesday, June 4, 2014 at 10:56pm*

**physics**

A 0.50 kg cue ball makes a glancing blow to a stationary 0.50 kg billiard ball. After the collision the cue ball deflects with a speed of 1.2 m/s at an angle of 30.0° from its original path. Calculate the original speed of the cue ball if the billiard ball ends up ...
*Wednesday, June 4, 2014 at 10:52pm*

**physics**

A 49-g bullet traveling at 290m/s penetrates a block of ice at 0∘C and comes to rest within the ice.Assuming that the temperature of the bullet doesn't change appreciably, how much ice is melted as a result of the collision? The heat of fusion of water is 333 kJ/kg.
*Wednesday, June 4, 2014 at 10:03pm*

**physics**

When a 310-g piece of iron at 180∘C is placed in a 95-g aluminum calorimeter cup containing 250 g of liquid at 10∘C, the final temperature is observed to be 32∘C. The value of specific heat for iron is 450 J/kg⋅C∘, and for aluminum is 900 J/kg&#...
*Wednesday, June 4, 2014 at 10:02pm*

**physics**

The value of specific heat for copper is 390 J/kg⋅C∘, for aluminun is 900 J/kg⋅C∘, and for water is 4186 J/kg⋅C∘.What will be the equilibrium temperature when a 275g block of copper at 255∘C is placed in a 145g aluminum calorimeter cup...
*Wednesday, June 4, 2014 at 10:02pm*

**physics**

An automobile cooling system holds 16 L of water. The specific heat of water is 4186 J/kg⋅C∘.How much heat does it absorb if its temperature rises from 16∘C to 94∘C?
*Wednesday, June 4, 2014 at 10:00pm*

**physics**

A bullet of mass 45 g is fired at a speed of 220 m/s into a 5.0 kg sandbag hanging from a string from the ceiling. The sandbag absorbs the bullet and begins to swing. To what maximum vertical height will it rise?
*Wednesday, June 4, 2014 at 9:59pm*

**physics**

A 0.50 kg cue ball makes a glancing blow to a stationary 0.50 kg billiard ball. After the collision the cue ball deflects with a speed of 1.2 m/s at an angle of 30.0° from its original path. Calculate the original speed of the cue ball if the billiard ball ends up ...
*Wednesday, June 4, 2014 at 9:58pm*

**physics**

A certain power plant puts out 520MW of electric power.Estimate the heat discharged per second, assuming that the plant has an efficiency of 34%
*Wednesday, June 4, 2014 at 9:55pm*

**physics**

alculate the final speed of a 1500 kg roller coaster if it has an initial speed of 16 m/s but reduces its elevation by 8.6 m by coasting down a frictionless incline.
*Wednesday, June 4, 2014 at 9:55pm*

**physics**

The exhaust temperature of a heat engine is 250∘C .What must be the high temperature if the Carnot efficiency is to be 35% ?
*Wednesday, June 4, 2014 at 9:53pm*

**physics**

a pole 10m long rests slantly against a vertical wall ab making 60 degrees with the horizontal (ground). find how faris the foot of the pole from the wall
*Wednesday, June 4, 2014 at 9:26pm*

**physics**

A charge of -2.68 ✕ 10-9 C is at the origin of a coordinate system, and a charge of 7.77 ✕ 10-9 C is on the x-axis at 2.00 m. At what two locations on the x-axis is the electric potential zero? (Hint: One location is between the charges, and the other is to the ...
*Wednesday, June 4, 2014 at 9:16pm*

**physics**

During the Olympic ice competition, Boris (m = 75 kg) glides at 1.8 m/s to a stationary Juliette (52 kg) and hangs on. How far will the pair slide after the collision if the coefficient of kinetic friction between the ice and their skates is .042?
*Wednesday, June 4, 2014 at 8:44pm*

**physics**

A 1.0 kg puck sliding at 15 m/s along some horizontal frictionless ice strikes and compresses a horizontal spring attached to one end of the ice rink. If the spring has a constant of 35 N/m, what is the maximum compression of the spring?
*Wednesday, June 4, 2014 at 8:41pm*

**physics**

A collision in Phystown is being analyzed by the O.P.P. accident analysis team. A 1000 kg Toyota known to be moving at 65 km/h [W] collided at an intersection with a 3000 kg SUV moving [N]. After the collision, the two vehicles "stuck" together and the police ...
*Wednesday, June 4, 2014 at 8:28pm*

**Physics**

A football player punts the ball at a 45.0o angle. Without an effect from the wind, the ball would travel 60.0 m horizontally. (a) What is the initial speed of the ball? (b) When the ball is near its maximum height it experiences a brief gust of wind that reduces its ...
*Wednesday, June 4, 2014 at 8:25pm*

**Physics**

A 250g wood block firmly attached to a horizontal spring slides along a table with a coefficient of friction of 0.40. A force of 30.N compresses the spring 20cm. If the spring is released from this position what will be the block's speed when it passes equilibrium position?
*Wednesday, June 4, 2014 at 8:14pm*

**physics**

A horizontal spring with spring constant of 120 N/m is compressed a distance of 0.25 m and placed in front of a ramp angled at 30° above the horizontal. A 1.5 kg ball is placed in front of it and released. How far will the ball roll up the 30° ramp? Again assume there ...
*Wednesday, June 4, 2014 at 7:51pm*

**physics**

A 2.2 kg bowling ball is dropped vertically from a height of 1.5 m onto a long compression spring (k = 150 N/m) placed vertically underneath it. What is the maximum compression of the spring?
*Wednesday, June 4, 2014 at 7:45pm*

**physics**

A 2.0 kg mass is fastened to a spring with force constant of 45 N/m. The mass is held motionless by a student at a position 15 cm below the spring's natural unstretched position. When the ball is released, what is the Fnet acting on it? What is the acceleration of the ball...
*Wednesday, June 4, 2014 at 7:13pm*

**Physics**

A ball is thrown straight upward and returns to the thrower's hand after 2.30 s in the air. A second ball is thrown at an angle of 42.0° with the horizontal. At what speed must the second ball be thrown so that it reaches the same height as the one thrown vertically?
*Wednesday, June 4, 2014 at 7:12pm*

**Physics**

Help me with this please A 6.0 m section of wire carries a current of 5.2 A from east to west in the earth's magnetic field of 1.0 × 10^-5 T at a location where the magnetic field points south. In which direction does the magnetic force act on the wire? north south ...
*Wednesday, June 4, 2014 at 6:30pm*

**Physics**

A soccer ball is kicked with a speed of 9.95m/s at an angle of 35.0∘ above the horizontal.If the ball lands at the same level from which it was kicked, how long was it in the air?
*Wednesday, June 4, 2014 at 6:22pm*

**Physics**

A small charge that has lost 5.0 X 10^3 electrons and has a mass of 2.0 x 10^-6 kg experiences an acceleration of 15ms^2 when placed at a point P in space. Determine the magnitude and direction of the electric field at P
*Wednesday, June 4, 2014 at 6:19pm*

**Physics**

The length of a box is reduced to two third of its original value and the width and height are tripled. Calculate the factor by which the volume has changed. Am I on the right track? If not please help I am stuck. Thanks. V=LWH V=(L-2/3)(3W)(3H)
*Wednesday, June 4, 2014 at 6:13pm*

**physics**

A 55 kg skateboarder accelerates down a ramp and hits the pavement moving at 5.6 m/s. If the pavement has a coefficient of friction of 0.11, how far will skateboarder glide before coming to a stop?
*Wednesday, June 4, 2014 at 5:35pm*

**physics**

4 kg block rests on a smooth horizontal surface,upper surface of 4 kg is rough.A block of mass 2 kg is placed on its upper surface.The acceleration of upper block with respect to earth when 4 kg mass is pulled by a horizontal force of 30N?coefficient of static friction=0.8 and...
*Wednesday, June 4, 2014 at 4:26pm*

**physics**

What is the kinetic energy of a 19 kg dog that is running at a speed of 7.7 m/s (about 17 mi/h)?
*Wednesday, June 4, 2014 at 3:23pm*

**physics**

"a drag racing car starts from rest at t= 0 and moves along astraight line with velocity given by V = bt^2 where b isconstant. The expression for the distance traveled by this car from its position at t = 0 is a)bt^3 b)bt^3/3
*Wednesday, June 4, 2014 at 2:08pm*

**Physics ||**

Q.1. Two wires each of length 40 m and diameter 2.6 mm, are connected in series. A potential difference of 50 V is applied between the ends of the composite wire. The resistances the wires are 0.13 Ω and 0.75 Ω, respectively. Determine: i) the current density in each...
*Wednesday, June 4, 2014 at 10:07am*

**physics**

a person walks due east for 10 meters and the due north for 10 meters. what is the total distance? b). what is the average speed of a car that travels 30 meters in 10 seconds, then another 50 meters in 30 seconds. Thank you for answering.
*Tuesday, June 3, 2014 at 11:14pm*

**Physics I NEED HELP WITH EQUATIONS**

A 7kg block is pulled at a constant velocity by a horizontal 25 N force - Calculate normal & gravitational forces - Calculate the applied & frictional forces - Calculate the coefficient of friction CAN SOMEONE PLEASE HELP ME WITH THE EQUATIONS FOR ALL OF THESE THINGS?
*Tuesday, June 3, 2014 at 10:55pm*

**physics**

a person walks due east for 10 meters and then due north for 10 meters. what is the total displacement?
*Tuesday, June 3, 2014 at 10:37pm*

**Physics**

i have a question on thin lens equation how do i know when di is positive or negative? also i have an example: A convex lens has a focal length of 60 cm. A candle is placed 50 cm from the lens. What type of image is formed and how far is the image from the lens? (Is my answer ...
*Tuesday, June 3, 2014 at 9:18pm*

**physics**

Two wires are made of the same material. The first wire dissipates power P with a current of I. If the second wire is 3 times as long and has twice the diameter, what will the current need to be through the second wire to dissipate the same power P as the first wire? A ...
*Tuesday, June 3, 2014 at 8:58pm*

**Physics**

Determine the final velocity of an alpha particle (3.2x10^-19) if it is placed in a 7.2x10^6 n/c uniform field. The mass of the alpha particle is 6.64x10^-27
*Tuesday, June 3, 2014 at 8:51pm*

**Physics**

Which of the following is an appropriate measure of electric power on a toaster label? A. 110 V B. 2.0 A C. 220 W D. 55 Ω
*Tuesday, June 3, 2014 at 8:41pm*

**physics**

In a rescue scene during the 911 crisis, a helicopter of mass 6000 kg accelerates upwards at the rate of 0.50 m/s2 while lifting a 2500 kg piece of concrete. What is the upward force exerted by the rotors of the helicopter? What is the tension in the cable attaching the ...
*Tuesday, June 3, 2014 at 8:37pm*

**Physics**

Am i correct? If a 10.0 kW device pulls 20.0 A of current, what voltage exists across it? A. 5.0 *10^0 V B. 5.0 *10^1 V C. 5.0 *10^2 V D. 5.0 *10^3 V <---
*Tuesday, June 3, 2014 at 8:08pm*

**physics**

A ball on the end of a string is moving in a horizontal circle. If the centripetal acceleration of the ball is 12 m/s2, while it is travelling at 3.0 m/s, what would the acceleration be if its speed increased to 4.0 m/s. Assume that the radius of rotation does not change.
*Tuesday, June 3, 2014 at 7:55pm*

**Physics**

What is the equivalent resistance of a parallel circuit with a 5.0 kΩ resistor, a 2.5 kΩ resistor, and 10.0 kΩ resistor? A. 0.10 kΩ b. 0.83 kΩ c. 10 kΩ d. 1.4 kΩ e. 18 kΩ
*Tuesday, June 3, 2014 at 7:49pm*

**Physics**

One 10.0 Ω resistor is wired in series with 10.0 Ω resistors in parallel. A 45.0 V battery supplies power to the circuit. What is the total current through the circuit? A. 3.0 A B. 1.5 A C. 0.75 A D. 0.33 A
*Tuesday, June 3, 2014 at 7:28pm*

**Physics**

Help me with this please A 10.0 Ω resistor is in parallel with a 20.0 Ω resistor and supplied by a 9.00 V battery. What is the total current passing through the circuit? A. 0.38 A B. 0.75 A C. 1.35 A D. 6.00 A
*Tuesday, June 3, 2014 at 6:48pm*

**physics**

A fisherman who lives in a high rise apartment building in Toronto, weighs a fish on a spring scale and records a 11.2 N reading. He reweighs the fish while he is in his elevator and records a reading of 13.1 N. What is the acceleration of the elevator at that moment?
*Tuesday, June 3, 2014 at 6:14pm*

**physics**

Sarah is pushing a 10 kg buggy and exerts a force of 100 N along the handle. If the handle is elevated at 37° to the horizontal, determine the component of the force that will move the buggy forward. If a frictional force of 60 N exists as she pushes it over a grass ...
*Tuesday, June 3, 2014 at 5:27pm*

**physics**

Calculate the average velocity for a remote controlled vehicle that starts with a speed of 1.0 m/s [forward] and then accelerates at 0.08 m/s2 [backward] for 4.0 s.
*Tuesday, June 3, 2014 at 5:23pm*

**physics**

The above graph represents the motion of two vehicles: A and B What is the acceleration of vehicle A during the first 5.0 s? Calculate the distance between vehicle A and B after 6.0 s? What is the instantaneous acceleration of vehicle A at the 10.0 s mark? What is the average ...
*Tuesday, June 3, 2014 at 5:02pm*

**Physics**

Calculate the maximum deceleration of a car that is heading down a 30.0° slope (one that makes an angle of 30° with the horizontal) under the following road conditions. You may assume that the weight of the car is evenly distributed on all four tires and that the ...
*Tuesday, June 3, 2014 at 4:49pm*

**physics**

An airplane requires 420 m of runway to take off from an airstrip. If the plane starts from rest and it takes 32 s to lift off, with what velocity does it leave the ground? What was the average acceleration of the plane?
*Tuesday, June 3, 2014 at 4:46pm*

**physics**

Jack is driving with a pail of water along a straight pathway at a steady 25 m/s when he passes Jill who is parked in her minivan waiting for him. When Jack is beside Jill, she begins accelerating at the rate of 4.0 × 10−3 m/s2 in the same direction that Jack is ...
*Tuesday, June 3, 2014 at 4:42pm*

**Physics**

am i correct? An electric oven has a resistance of 10.0Ω and a voltage of 220 V. How much current does it draw? A. 2.2 A B. 22 A <--- c. 220 A d. 2,200 A
*Tuesday, June 3, 2014 at 4:41pm*

**physics**

A lifeguard who can swim at 1.2 m/s in still water wants to reach a dock positioned perpendicularly directly across a 550 m wide river. If the current in the river is 0.80 m/s, how long will it take the lifeguard to reach the dock? If instead she had decided to swim in such a ...
*Tuesday, June 3, 2014 at 4:32pm*

**Physics**

Help me with this question, please How will the total voltage of a string of light bulbs in series change as you add more bulbs to the string? A. The total voltage will decrease B. The total voltage will stay the same C. The total voltage will increase d. You cannot predict ...
*Tuesday, June 3, 2014 at 4:13pm*

**physics **

A pilot is flying from City A to City B which is 300 km [NW]. If the plane will encounter a constant wind of 80 km/h from the north and the schedule insists that he complete his trip in 0.75 h, what air speed and heading should the plane have?
*Tuesday, June 3, 2014 at 4:02pm*

**physics**

A passenger on a train notices that a 2.00 kg mass is displaced 10.0° from the vertical as the train accelerates. (a) What is the acceleration of the train? (b) What would the acceleration be if the mass was 5.00 kg? c. What would angle have to be to indicate a horizontal ...
*Tuesday, June 3, 2014 at 3:17pm*

**Physics**

A 15.0 kΩ resistor is hooked up to a 45.0 V battery in a circuit with a switch. a.) What is the current flowing through the resistor? b.) What is the power dissipated by the resistor?
*Tuesday, June 3, 2014 at 3:16pm*

**Physics**

I know this is long but can someone just explain it to me? Please? Don't have to give the answer, I'm just confused :( 1. An experiment was devised to investigate the effects on the temperature of a cup of hot tea when lemon juice is added at different time intervals. ...
*Tuesday, June 3, 2014 at 2:21pm*

**Physics**

Consider the 52.0-kg mountain climber in the figure to the right. Find (a) the tension in the rope and (b) the force that the mountain climber must exert with her feet on the vertical rock face to remain stationary. Assume that the force is exerted parallel to her legs. Also, ...
*Tuesday, June 3, 2014 at 12:12pm*

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