Unit 5: Energy Exam Review

A block of mass M is connected to spring on a frictionless surface. When the block is moved to the left so that the spring is compressed, the potential energy is PE. Another block with a mass of 3M is attached to the same spring and compressed the same mount. What is the potential energy stored for the block of 3M?

• 1/3 PE

• PE

• 3 PE

• 9 PE

The table shown has the information about the daily use of some typical appliances. Which appliance uses the most energy?

• Cell Phone Charger

• Desk Lamp

• Mini Fridge

• Television

A person carries a backpack that has a total weight of 800 N. How much work is done when she climbs up a 9 m flight of stairs in 10 s?

• 7200 J

• 720 J

• 60 J

• 50 J

A physics student is conducting an experiment where a cart is going down a ramp. After several trials, the student calculates that the kinetic energy at the bottom of the ramp is LESS THAN the potential energy at the top of the ramp. Which of the following best explains the difference in energies?

• The car gained a small amount of mass while it moved down the ramp.

• The student accidently accelerated the car at the top of the ramp.

• The measured height of the ramp was actually less than the actual height.

• The student didn't account for the effect friction would have on the cart as it moves down the ramp.

Annie and her friend need to make a ramp to help move a new couch into a home. They must take the couch up 3 meters of stairs. Which of the answers below correctly compares the Force and Work required using each ramp?

• The 15 m ramp will require a smaller force and require more Work

• The 5 m ramp will require a larger force and require more Work

• Both ramps will require the same force and the same Work

• The 5 m will require a larger force and require the same Work

Which graph shows an object that conserved its Total Mechanical Energy?

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There are 4 identical carts each with a mass of 0.5 kg. Blocks of a mass 1.0 kg are randomly placed on the carts. Each of the 4 carts goes up a ramp where every box is 1.0 meters high. Which cart has the least potential energy at the top of the ramp?

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A block slides across a flat, horizontal surface to the right. Each dot represents the blocks position after 1 second of time. Which of the following diagrams represents the block losing kinetic energy.

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A 2 kg block is placed at the top of a ramp with a height of H. The block’s velocity while sliding down the incline is shown in the graph. How could a student use the graph to determine the total mechanical energy of the block at the bottom of the ramp? Friction is negligible.

• Use mgy₀ with m=2 kg and y₀ equal to the area between the horizontal axis and the curve

• Use ½ mv_f² with m=2 kg and v_f equal to the final velocity of the object that can be found from the graph.

• Use Fd with F equal to the normal force exerted on the block and d equal to the area between the horizontal axis and the curve.

• The answer cannot be determined without knowing the initial height of the object above the ground.

A 10 kg block is pushed up a 3.0 m high incline as shown. The block is pushed a distance of 15.0 m up the incline. What is the gravitational energy of the block at the top of the incline? Use g=10 m/s²

• 0 J

• 30 J

• 150 J

• 300 J