Work, power & energy Questions and Answers

Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s. a. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy? b. What would be the ΔKE in this problem, and what would be the work done on the roller coaster?

The block below is pulled a distance of 2.50 m by a horizontal force F = 4.50 N. How much work is done by the force? Show your work and include units. Show your work below and include units.

3. Two objects of different mass start from rest, are pulled by the same net force (magnitude and direction), and are moved through the same displacement. The work done on object 1 is 500 J. After the force has pulled each object, object 1 moves twice as fast as object 2. Answer the following questions. Show your work below and include units. (a) How much work is done on the object 2? (b) What is the kinetic energy of object 1 after being pulled? (c) What is the kinetic energy of object 2 after being pulled? (d) What is the ratio of the mass of object 1 to the mass of object 2?

An object of mass m = 0.550 kg is lifted from the floor to a height of 3.50 m at a constant speed. Answer the following questions, show your work below and include units. (a) How much work is done by the lifting force? (b) How much work is done by the gravity of the object? (c) What is the net work done on the object? (d) What is the change in kinet energy the object? (e) If the object in this question is released from rest after it is lifted, what is its kinetic energy just before it hits the floor? What is its speed?

2. A 1000kg car traveling at 40m/s slows to 20m/s. a. Find initial kinetic energy. b. Find final kinetic energy. c. How much work is done on the car in slowing it down? d. [What force does the work on the car?]

A car of mass 1063 kg climbs a 5.0° slope at a constant speed of 72.0 km/h. Assuming that air resistance may be neglected, at what rate must the engine deliver mechanical energy to the car? 14 kW 18 kW 231 kW 20 kW

At a certain point on the trackway, a roller coaster car has 27,000 J of potential energy and 132,000 J of kinetic energy. The value 159,000 J equals this point. the total internal and external energy the total mechanical energy plus dissipated energy the total mechanical energy minus dissipated energy the total mechanical energy

A 3.00-kg flowerpot is perched on a windowsill that is 8.20 m from the ground. How much gravitational potential energy does the flowerpot have relative to the ground? 241 J 201 J 24 J 29.4 J

3. A 0.05-kg car starts from rest at a height of 0.95 m. Assuming no friction, what is the kinetic energy of the car when it reaches the bottom of the hill? (Assume g= 9.81 m/s²) A. 0.466 J B. 0.308 J C. 4.317 J D. 0.0475 J

9. The size of the water droplets represents the amount of energy applied to create a wave. What kind of relationship (direct, inverse) is there between the energy applied and the height of a wave? 10. Think about comparing the wavelength to the frequency. Go back and change these variables if you need to. What kind of relationship is there between wavelength and frequency?

A firefighter climbs a ladder at a speed of 1.4 m/s. The ladder is 5.0 m long, and the firefighter weighs 65 kg. a) Determine the firefighter's power output while climbing the ladder. (890 W) b) How long does it take her to climb the ladder? (3.6 s)

How much work does a supermarket checkout attendant do on a can of soup he pushes 0.600 m horizontally with a force of 5.00 N? Express your answer in joules and kilocalories.

A Mexican Jumping Bean jumps with the aid of a small worm that lives inside the bean. If a bean of mass 1.8 g jumps 1.0 cm from your hand into the air, how much potential energy has it gained in reaching its highest point? What is its speed as the bean lands back in the palm of your hand?

You perform the Hooke's Law experiment and create a plot of Displacement vs. Force. You add a linear fit and find the following equation for the line: y=0.180x -0.030 What is the spring constant, k (in N/m or kg/s²)?

Problem 1) My cat, Boo, is very small. The vet didn't believe their assistant when the assistant said Boo weighed only 6.0 lbs. Boo jumps from my desk and lands with a velocity of 0.50 m/s directed downward. Calculate her momentum as she lands. Hint: remember to convert. Problem 2) Mercury has a mass of 3.285x102³ kg, and orbits the Sun in an approximately circular orbit with radius of 57.90 million km in a period of 88 days. a) Calculate the tangential speed of Mercury. Hint: Recall what we learned about uniform circular motion. b) Calculate the magnitude of the linear momentum of Mercury.

A worker lifts a heavy 15 kg box from the floor up to a height of 2 meters in about 6 seconds. Assuming there is a loss due to heat of 20 J each time then what power would actually be used to move the box?

A billiards cue ball moves towards two stationary balls that are next to each other (one in front of the other). All the balls just move in a single direction, with the cue ball initially moving in the +x direction. Assume any collision between the balls conserves momentum. Each ball has a mass of 0.17 kg. The cue ball's initial velocity is +20 m/s and the other two balls are sitting still. After the cue ball hits the first still ball, the first still ball hits the second still ball immediately. The result is after the collisions, the cue ball moves backwards, -2 m/s in the x-direction. The first still ball (in the middle), moves forward in the x-direction with velocity +9 m/s in the x-direction. To conserve momentum, what will the velocity of the second (initially) still ball be? Show whether the kinetic energies of the balls are conserved in this set of collisions or not (consider the three balls as one system). If energy is gained or lost by the balls, calculate how much. If kinetic energy was lost, where might the energy have gone? Give at least 2 possibilities.

You are at the controls of a particle accelerator, sending a beam of 4.20x107 m/s protons (mass m) at a gas target of an unknown element. Your detector tells you that some protons bounce straight back after a collision with one of the nuclei of the unknown element. All such protons rebound with a speed of 3.90x107 m/s. Assume that the initial speed of the target nucleus is negligible and the collision is elastic. Part A Find the mass of one nucleus of the unknown element. Express your answer in terms of the proton mass m. Part B What is the speed of the unknown nucleus immediately after such a collision? Express your answer in meters per second.

Two figure skaters, one weighing 635 N and the other 775 N, push off against each other on very smooth ice. ▼ V= Submit Part B K = Submit Part C VAE How much kinetic energy is "created" during the skaters' maneuver? Express your answer in joules. Request Answer AEO Request Answer Where does this energy come from? Submit ? m/s ? Request Answer J The kinetic energy of the system was produced by the work the two skaters do on each other. The kinetic energy of the system was produced by the work the lighter skater does on the heavier one. Review 1 Constants The kinetic energy of the system was produced by the work the heavier skater does on the lighter one. The kinetic energy of the system was produced by the work done by ice on the two skaters.

An book fell from a shelf 1.5 meters from the ground. If it took the book 3 seconds to hit the ground, what was the velocity of the book? O 3 m/s O 0.5 m/s O 1 m/s O 1.5 m/s

In a circuit, 20 C of charge is passed through a battery in a given time. The plates of the battery are maintained at P.D. of 20 V. How much work is done by the battery? Correct Answer A. 400 J B. 300 J C. 200 J D. 100 J

You are in a zombie-themed paintball shooting range, armed with a spring-loaded paintball gun. The spring mechanism, with a spring constant of 8.6 x 104 N/m compresses 1.5 cm in order to shoot out a 3.0 gram paintball. You are at the bottom of a set of stairs and see a zombie pop up at the top of the stairwell. If the zombie is located a vertical distance of 15 meters above you, with what speed does the paintball hit the zombie? Ignore air resistance.

A shooting star is the trail of a meteor a chunk of debris hurtling through Earth's atmosphere. As drag slows down the meteor, its energy is converted into thermal energy. A typical meteor may only weigh 2 grams, and enters the Earth's atmosphere at a speed of 100,000 mph. Assuming that all of its energy is converted into thermal energy over a time of just 3 seconds, what is the power output of the shooting star? How does this compare to the power output of a typical household light bulb?

A 3500 kg amateur rocket is given a velocity 820 m/s. How many meters high can the rocket be expected to rise before falling back to Earth? How high is this in miles?. [recall that 1 meter = 3.28 ft]

A 0.300 kg puck, initially at rest on a horizontal, frictionless surface, is struck, is - struck by a 0.200 kg puck moving initially along the x axis with a speed of 2.00 m/s. After the collision, the 0.200 kg puck has a speed of 1.00 m/s at an angle of 0 = 53.0⁰ to the positive x axis (see Figure 9.11). Determine the velocity of the 0.300 - kg puck after the collision.

A boy reaches out of a window and tosses a ball straight up with a speed of 10 m/s. The ball is 20 m above the ground as he releases it. Use coservation of energy to find the ball's speed as it passes the window on its way down. Express your answer in meters per second. Uwindow =

Problem 5) A spring-loaded cannon is often used during projectile motion or conservation of energy physics labs. Suppose you place a 3.47x10-³ kg steel ball into the cannon. The cannon is pointed straight up, the ball is placed into the cannon, and you compress the spring by 0.091 m using a stick. a) Calculate the work done by gravity as you compress the spring. b) Suppose the spring has a spring constant of 8.42 N/m. Calculate the work done by the spring as it is compressed. c) Suppose the spring is now released and the ball rises with the spring. Calculate the net work done on the ball when the spring reaches its uncompressed position (its equilibrium position). d) The ball was initially at rest. Calculate its speed given at the position described in part (c).

Suppose a sled is being pulled by a Bernese Mountain dog across the snow (his name was Berg). The 42.9 kg sled starts at rest and speeds up to 2.59 m/s over 5.64 m. a) Calculate the change in kinetic energy of the sled. b) Calculate the average net force on the sled. c) Calculate the average power exerted on the sled this motion occurred over 10.7 s.

A 500-kg dragster accelerates from rest to a final speed of 96 m/s in 400 m (about a quarter of a mile) and encounters an average frictional force of 1200 N. Calculate the average power output of the dragster if this takes 7.5 s. Hint: The dragster does work to speed up and to counter friction.

An object of mass 20.0 kg is at rest at the top of an inclined plane whose length is 12.0 m and which makes an angle of 30.0° with the horizontal. The coefficient of kinetic friction between the object and the inclined plane is 0.400. The object is released and slides down the plane. What is the kinetic energy of this object at the bottom of the inclined plane? Use g = 10.0 m/s². 173 J 200 J 600 J 369 J 300 J

Two objects were lifted by a machine. One object had a mass of 2 kilograms, and was lifted at a speed of 2 m/sec. The other had a mass of 4 kilograms and was lifted at a rate of 3 m/sec. a. Which object had more kinetic energy while it was being lifted? b. Which object had more potential energy when it was lifted to a distance of 10 meters? Show your calculation.

A man lifts a 20.0-kg bucket of concrete from the ground up to the top of a 25.0-m tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building. How much work was done by the man in lifting the bucket? 4.90 kJ 500 J 160 J 660 J 5.06 kJ

In the picture, Electrical energy goes into a lightbulb, and Heat and Light come out. Based on the Law of Conservation of Energy and the amounts shown in the picture, how much LIGHT energy is coming out? 60 Joules 105 Joules 45 Joules 15 Joules

If the car were approaching the hill instead at 30 m/s, would it roll to A car moving at 15 m/s approaches a hill. If the car were put in neutral, it would roll up the hill to stop at the same elevation? You may ignore the effects of friction in your calculations. Yes, the car would roll to a stop at the same elevation. That elevation depends on the weight of the car, not the speed of the car when it reaches the hill. No, the car would roll to a stop at four times the elevation. No, the car would roll to a stop at twice the elevation.

A pulley with a lot of friction is very squeaky and is only 73% efficient. The pulley is used to lift a 58 kg mass to a height of 3.0 m by a rope that is pulled 18.0 m. What is the force exerted on the rope?

A 0.60 kg block attached to a spring with force constant 130 N/m is free to move on a frictionless, horizontal surface as in the above figure. The block is released from rest when the spring is stretched 0.13 m. At the instant the block is released, find (a) the force on the block and (b) its acceleration.

A hoop of radius 0.50 m and a mass of 0.20 kg is released from rest and allowed to roll down an inclined plane. How fast is it moving after dropping a vertical distance of 6.05 m? 3.8 m/s 7.7 m/s 5.4 m/s 2.2 m/s

Under the influence of conservative forces only, an object of mass 9 kg is displaced from point A to point B. Its potential energy and speed at point A respectively are 450 J and 10 m/s. Its potential energy at point B is -1000 J. 20.548 m/s 15.023 m/s 11.164 m/s 2.504 m/s 34.857 m/s

A weight lifter lifts a 280-N set of weights from ground level to a position over his head, a vertical distance of 1.95 m. How much work does the weight lifter do, assuming he moves the weights at constant speed?

Two blocks A and B of masses m and 2m, respectively, are connected with the help of a spring having spring constant, k as shown in Fig. Initially, both the blocks are moving with same velocity v on a smooth horizontal plane with the spring in its natural length. During their course of motion, block B makes an inelastic collision with block C of mass m which is initially at rest. The coefficient of restitution for the collision is 1/2. The maximum compression in the spring is?

A piano with a mass of 124 kg is lifted 10 m above the ground in 4 s by a crane. What is the power used by the crane, measured in watts (W)?

A ball of mass 0.100 kg traveling with 5.00 m/s had a head on collision with a ball of mass 0.200 kg initially at rest. After the collision, the second ball has a velocity of 2.00 m/s to the same direction as the first ball. (a) Find the velocity of the first ball. (b) Find the mechanical energy loss during the collision (c) what would happens to the lost energy? (d) Is this collision elastic or inelastic?

A skier traveling 11.0 m/s reaches the foot of a steady upward 18° incline and glides 14 m up along this slope before coming to rest. What was the average coefficient of friction?

A horizontal spring with a spring constant of 130 is attached to a wall. Someone comes along and presses against it, compressing it by 1.4 meters. How much energy is stored in the spring? Do all your calculations in SI and submit your answer without units.

A person of mass 60 kg descends down a slide with a height of 3.8 m. The person starts from rest and reaches the bottom with a speed of 3.11 m/s. How much thermal energy was generated due to friction? (In other words, how much work was done by friction. There are multiple ways this can be solved. I suggest using your general energy conservation equation.)

A tractor-trailer truck traveling at a speed of 4.2 m/s with a mass of 19,589 kg is traveling on a horizontal surface when it strikes a gigantic horizontal spring which brings the truck to rest in 15 meters. What is the stiffness constant of the spring? Do all your calculations in Sl and submit your answer without units.

A spring has a spring stiffness constant & of 85.0 N/m. How much must this spring be compressed to store 45.0 J of potential energy? Express your answer to three significant figures and include the appropriate units.

How much work must be done to stop a 1075-kg car traveling at 110 km/h? Express your answer to two significant figures and include the appropriate units.

If the gravitational potential energy of the book-Earth system increases by 8.84 J. how high is the bookshelf above the desk? Express your answer to three significant figures and include appropriate units.

The potential energy of a particle moving along the axis is shown in the figure. (Figure 1) When the particle is at = 1.0 m it has 3.6 J of kinetic energy. Give approximate answers to the following questions. What is the largest value of a the particle can reach?