Top-Rated Free Essay
Preview

EXERCISE 5 Work And Energy

Good Essays
877 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
EXERCISE 5 Work And Energy
EXERCISE 6

1. A shopper in a supermarket pushes a cart with a force of 35 N directed at an angle of 25° downward from the horizontal. Find the work done by the shopper as she moves down a 50-m length of aisle.
1.6 kJ

2. A horizontal force of 150 N is used to push a 40.0-kg packing crate a distance of 6.00 m on a rough horizontal surface. If the crate moves at constant speed, find (a) the work done by the 150-N force and (b) the coefficient of kinetic friction between the crate and surface.
900J, 0.383

3. A block of mass 2.50 kg is pushed 2.20 m along a frictionless horizontal table by a constant 16.0-N force directed 25.0° below the horizontal. Determine the work done by (a) the applied force, (b) the normal force exerted by the table, (c) the force of gravity, and (d) the net force on the block.
31.9J, 0, 0, 31.9J

4. A mechanic pushes a 2.50 × 103-kg car from rest to a speed of v, doing 5 000 J of work in the process. During this time, the car moves 25.0 m. Neglecting friction between car and road, find (a) v and (b) the horizontal force exerted on the car.
2.0 ms-1, 200 N

5. A person doing a chin-up weighs 700 N, exclusive of the arms. During the first 25.0 cm of the lift, each arm exerts an upward force of 355 N on the torso. If the upward movement starts from rest, what is the person’s velocity at that point?
0.265 ms‑1, upwards

6. A crate of mass 10.0 kg is pulled up a rough incline with an initial speed of 1.50 m/s. The pulling force is 100 N parallel to the incline, which makes an angle of 20.0° with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 5.00 m. (a) How much work is done by gravity? (b) How much mechanical energy is lost due to friction? (c) How much work is done by the 100-N force? (d) What is the change in kinetic energy of the crate? (e) What is the speed of the crate after being pulled 5.00 m?
-168 J, -184J, 500J, 148J, 5.64 ms-1

7. A 2 000-kg car moves down a level highway under the actions of two forces: a 1 000-N forward force exerted on the drive wheels by the road and a 950-N resistive force. Use the work–energy theorem to find the speed of the car after it has moved a distance of 20 m, assuming that it starts from rest.
1.0 ms-1

8. An athlete on a trampoline leaps straight up into the air with an initial speed of 9.0 m/s. Find (a) the maximum height reached by the athlete relative to the trampoline and (b) the speed of the athlete when she is halfway up to her maximum height.
4.1 m, 6.4 ms-1
9. A daredevil on a motorcycle leaves the end of a ramp with a speed of 35.0 m/s as in the figure 1. If his speed is 33.0 m/s when he reaches the peak of the path, what is the maximum height that he reaches? Ignore friction and air resistance.
6.94 m

10. A child and a sled with a combined mass of 50.0 kg slide down a frictionless slope. If the sled starts from rest and has a speed of 3.00 m/s at the bottom, what is the height of the hill?
0.459 m

11. A bead of mass m = 5.00 kg is released from point A and slides on the frictionless track shown in Figure 2. Determine (a) the bead’s speed at points B and C. (b) the net work done by the force of gravity in moving the bead from A to C.
5.94 ms-1, 7.67 ms-1, 147 J

Figure 2

12. A 0.250-kg block is placed on a light vertical spring (k = 5.00 × 103 N/m) and pushed downwards, compressing the spring 0.100 m. After the block is released, it leaves the spring and continues to travel upwards. What height above the point of release will the block reach if air resistance is negligible?
10.2 m

13. A 2.1 × 103-kg car starts from rest at the top of a 5.0-m-long driveway that is inclined at 20° with the horizontal. If an average friction force of 4.0 × 103 N impedes the motion, find the speed of the car at the bottom of the driveway.
3.8 ms-1

14. A skier of mass 70 kg is pulled up a slope by a motor-driven cable. (a) How much work is required to pull him 60 m up a 30° slope (assumed frictionless) at a constant speed of 2.0 m/s? (b) What power must a motor have to perform this task?
21 kJ, 686 W

15. The electric motor of a model train accelerates the train from rest to 0.620 m/s in 21.0 ms. The total mass of the train is 875 g. Find the average power delivered to the train during its acceleration.
8.01 W

You May Also Find These Documents Helpful

  • Good Essays

    Mae219 Unit 9 Study Guide

    • 613 Words
    • 3 Pages

    A piston cylinder device initially contains 0.07m3 of nitrogen gas at 130KPa and 120oC. The nitrogen is now expanded polytropically to a state of 100KPa and 100oC. Determine the boundary work done during this process.…

    • 613 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Nt1310 Unit 4

    • 313 Words
    • 2 Pages

    2) In Fig. 6-33, two blocks are connected over a pulley. The mass of block A is 7.8 kg and the coefficient of kinetic friction between A and the incline is 0.13. Angle θ of the incline is 44°. Block A slides down the incline at constant speed. What is the mass of block B?…

    • 313 Words
    • 2 Pages
    Good Essays
  • Satisfactory Essays

    6. A student pushes a 0.5 kg mass along a horizontal ramp according to the F-d graph shown below. a) How much work did the student do on the mass? b) What speed did the mass leave the…

    • 388 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Practice Quiz

    • 5122 Words
    • 42 Pages

    A horizontal force of 100 N is used to pull a crate, which weighs 500 N, at constant velocity across a horizontal floor. What is the coefficient of kinetic friction? π ℓ, the distance traveled. 2 2. T ℓ 3.…

    • 5122 Words
    • 42 Pages
    Satisfactory Essays
  • Satisfactory Essays

    1. A 1400 kg car is travelling at 25 m/s on a circular hill of radius 210 m. What is the normal force on this car at the top of the hill?…

    • 514 Words
    • 3 Pages
    Satisfactory Essays
  • Good Essays

    10. An 80 kg trucker loads a crate as shown below. He pushes the 40 kg box such that his arms are parallel to the ground. He pushes with a 100 N force. How much work is done by the trucker on the box?…

    • 510 Words
    • 3 Pages
    Good Essays
  • Satisfactory Essays

    The 5th wave

    • 2264 Words
    • 10 Pages

    1. A 1.08 x 103 kg car uniformly accelerates for 12.0s from rest. During this time the car travels 132 m north. What is the net force acting on the car during this acceleration 2. A net force of 12 N is exerted on and to cause it to accelerate at a rate of 0.03 m/s2. Determine the mass of the encyclopedia. HYPERLINK http//fc.codmanacademy.org/branches/physicsofdriving2/pushingbuses.jpg INCLUDEPICTURE http//fc.codmanacademy.org/branches/physicsofdriving2/images/pagemaster/pushingbuses.jpg MERGEFORMATINET 5. 4. How much force does a 40,000kg rocket develop toaccelerate 2m/s2 5. Block 1 is 12kg and block 2 is 23kg calculate the force that is needed to move the blocks a distance of 3 meters in 4 seconds. SHAPE MERGEFORMAT 6. Peter is trying to move a large rock across the table, if the rock is 12kg how much force does peter need to exert to move the rock with acceleration of 0.5 m/s2 . 7. Angel is moving a small rock easily by exerting a force of 2N to move the rock from rest to 0.7m/s in 3 seconds, what is the mass of the small rock. 3. Calculate the net force that Eddie has to exert on the van to move with an acceleration of 0.013m/s2…

    • 2264 Words
    • 10 Pages
    Satisfactory Essays
  • Powerful Essays

    Midterm Review

    • 1913 Words
    • 8 Pages

    10. Two children push on a heavy crate that rests on a basement floor. One pushes horizontally with a force of 150 N and the other pushes in the same direction with a force of 180 N. The crate remains stationary. Show that the force of friction between the crate and the floor is 330 N.…

    • 1913 Words
    • 8 Pages
    Powerful Essays
  • Powerful Essays

    Mass and Kinetic Energy

    • 965 Words
    • 4 Pages

    a) When the 3 kg weight is moving with a speed of 2.2 m/s, what is the kinetic energy of the entire system?…

    • 965 Words
    • 4 Pages
    Powerful Essays
  • Good Essays

    Physics Past Hsc Q's

    • 1033 Words
    • 5 Pages

    300 m (a) Calculate the horizontal component of the stone’s initial velocity. Show your working. ............................................................................................................................... ............................................................................................................................... (b) Calculate the vertical component of the stone’s initial velocity. Show your working.…

    • 1033 Words
    • 5 Pages
    Good Essays
  • Good Essays

    Final Study Guide

    • 1941 Words
    • 8 Pages

    2. A car travels at a speed of 25 m/s on a flat stretch of road. The driver must maintain pressure on the accelerator to keep the car moving at this speed. What is the net work done on the car over a distance of 250 m?…

    • 1941 Words
    • 8 Pages
    Good Essays
  • Satisfactory Essays

    Friction and Shoe Slide

    • 294 Words
    • 2 Pages

    In Part 1, did the force of friction on the shoe depend on the weight of the shoe? If the two are related, why are they? What is the slope of the line on the graph of force of friction vs. weight, and what does that number represent? Explain using your data.…

    • 294 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Newton's 1st Law

    • 970 Words
    • 4 Pages

    A stalled car is being pushed up a hill at constant velocity by three people. The net force on the car is…

    • 970 Words
    • 4 Pages
    Good Essays
  • Good Essays

    physics

    • 5301 Words
    • 22 Pages

    d) Know and understand that if the resultant force acting on a stationary object is:…

    • 5301 Words
    • 22 Pages
    Good Essays
  • Good Essays

    Force and Kinetic Energy

    • 814 Words
    • 4 Pages

    The block moves up an incline with constant speed. What is the total work WTotal done on the block by all forces as the block moves a distance L = 3.40 m up the incline? Include only the work done after the block has started moving at constant speed, not the work needed to start the block moving from…

    • 814 Words
    • 4 Pages
    Good Essays

Related Topics