Exam 6: Work and Energy

An object with a mass of 10 kg is initially at rest at the top of a frictionless inclined plane that rises at 30° above the horizontal. At the top, the object is initially 8.0 m from the bottom of the incline, as Shown in the figure. When the object is released from this position, it eventually stops at a distance D from the bottom of the inclined plane along a horizontal surface, as shown. The coefficient of Kinetic friction between the horizontal surface and the object is 0.20, and air resistance is negligible. Find the distance d.

How much work would a child do while pulling a 12-kg wagon a distance of 4.3 m with a 22 N force?

A 5.0-N projectile leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise If there was no air resistance?

An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the object?

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?

A certain car traveling at 34.0 mph skids to a stop in 29 meters from the point where the brakes were applied. In approximately what distance would the car have stopped had it been going 105.4 Mph?

The graphs shown show the magnitude F of the force exerted by a spring as a function of the distance x the spring has been stretched. For which one of the graphs does the spring obey Hooke's Law? a) b) c) d) e)

A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this force as a function of the position of the object. How much work does the force do as the object moves from 4 m to 6 m?

A 10-kg dog is runnng with a speed of 5.0 m/s. What is the minimum work required to stop the dog in 2.40 s?

Water flows over a waterfall that is 20 m high at the rate of $4.0 \times 10 ^ { 4 } \mathrm {~kg} / \mathrm { s }$ If this water powers an electric generator with a 40% efficiency, how many watts of electric power can be supplied?

If a stone is dropped with an initial gravitational potential energy of 100 J but reaches the ground with a kinetic energy of only 75 J, this is a violation of the principle of conservation of energy.

How high a hill would a 75-kg hiker have to climb to increase her gravitational potential energy by 10,000 J?

You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same Conditions?

Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?

A 35-N bucket of water is lifted vertically 3.0 m and then returned to its original position. How much work did gravity do on the bucket during this process?

The horizontal force that an animal exerts on a large fruit it has found is observed and is shown in the graph in the figure. If the fruit was initially sliding on the frictionless ground at 5.5 cm/s when The animal first grabbed it, by how much did the animal change its kinetic energy during this Encounter?

A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this force as a function of the position of the object. How much work does the force do as the object moves from 0 to 15 m?

The resultant force on an object over a 0.50-s time interval is plotted in the graph in the figure. How much work did this force do on the object during the 0.50-s interval?

The net force that an animal exerts on a large fruit it has found is observed over a 10-s interval and is shown in the graph in the figure. What was the average power delivered to the fruit by the Animal over this time interval?

Which one has larger kinetic energy: a 500-kg object moving at 40 m/s or a 1000-kg object moving at 20 m/s?