FiltersDone

Question type

Essay

Multiple Choice

Short Answer

True False

Matching

Exam 10: Energy and Work

Show Answer

Share

---

All types

Filters

Study FlashcardsPractice ExamLearn

Question 111

Short Answer

Review LaterAdd Note

Review Later

A typical incandescent light bulb consumes 75 W of power and has a mass of 30 g. You want to save electrical energy by dropping the bulb from a height great enough so that the kinetic energy of the bulb when it reaches the floor will be the same as the energy it took to keep the bulb on for 1.0 hour. From what height should you drop the bulb, assuming no air resistance and constant g?

Correct Answer

verified

Show Answer

Question 112

Multiple Choice

Review LaterAdd Note

Review Later

A uniform solid cylinder with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 33.4 rpm. What is its kinetic energy?

A) 0.18 J
B) 0.092 J
C) 0.96 J
D) 1.1 J
E) 17 J

F) A) and C)
G) A) and E)

Correct Answer

verified

Show Answer

Question 113

Multiple Choice

Review LaterAdd Note

A child pulls on a wagon with a force of $75 \mathrm {~N}$ If the wagon moves a total of $42 \mathrm {~m}$ in $3.1 \mathrm {~min} ,$ what is the average power delivered by the child?

A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii. If the three of them are released simultaneously at the top of an inclined plane and do not slip, which one will reach the bottom first?

What is the kinetic energy of a 120-cm thin uniform rod with a mass of 450 g that is rotating about its center at 3.60 rad/s?

How large a net force is required to accelerate a 1600-kg SUV from rest to a speed of 25 m/s in a distance of 200 m?

A 60-kg skier starts from rest from the top of a 50-m high slope. If the work done by friction is -6.0 kJ, what is the speed of the skier on reaching the bottom of the slope?

The figure shows two blocks connected by a light cord over a pulley. This apparatus is known as an Atwood's machine. There is no slipping between the cord and the surface of the pulley. The pulley itself has negligible friction and it has a radius of 0.12 m and a mass of 10.3 kg. We can model this pulley as a solid uniform disk. At the instant that the heavier block has descended 1.5 m starting from rest, what is the speed of the lighter block?

In a perfectly elastic collision, a 400-g ball moving toward the east at 3.7 m/s suddenly collides head-on with a 200 g ball sitting at rest. (a)Determine the velocity of the first ball just after the collision. (b)Determine the velocity of the second ball just after the collision. (c)Is kinetic energy conserved in this collision? How do you know?

In a certain nuclear reactor, neutrons suddenly collide with carbon nuclei, which have 12 times the mass of neutrons. In a head-on elastic collision with a stationary carbon nucleus, what fraction of its initial speed does the neutron have after the collision?

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car.

A 1-kg ball is released from a height of 6 m, and a 2-kg ball is released from a height of 3 m. Air resistance is negligible as they fall. Which of the following statements about these balls are correct? (There could be more than one correct choice.)

A rock falls from a vertical cliff that is 4.0 m tall and experiences no significant air resistance as it falls. At what speed will its gravitational potential energy (relative to the base of the cliff) be equal to its kinetic energy?

How fast must a 6.0-kg cat run to have a kinetic energy of 150 J?

A solid uniform sphere of mass 120 kg and radius 1.7 m starts from rest and rolls without slipping down an inclined plane of vertical height 5.3 m. What is the angular speed of the sphere at the bottom of the inclined plane?

When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high?

A 60-kg skier pushes off the top of a frictionless hill with an initial speed of 4.0 m/s. How fast will she be moving after dropping 10 m in elevation? Air resistance is negligible.

A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system

The kinetic friction force that a horizontal surface exerts on a 60.0-kg object is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?