Unit 5 Review

Front

Potential energy comparison of two blocks: A block of mass M is placed at height H. A block of mass 2M is placed at the same height. How does the potential energy (PE) of the second block compare to the first?

Back

2 PE

Answer explanation

Potential is directly related to height AND mass

Front

A firefighter carrying his gear has a total weight of 1200 N. How much work does he do when he climbs a 20 m ladder? (HINT: W = F*d)

Back

24000 J

Answer explanation

Since Work = Force*Distance, we multiply our force (vertical - our weight) times our distance (vertical - going UP the ladder)

Front

What needs to be true for energy to be conserved when rolling a marble down a ramp?

Back

KE at the end should match the initial PE

Answer explanation

Friction can take away our energy. It is conserved if the total initial energy is equal to the total final energy.

Front

Using the graph, what can we tell about potential energy?

Back

Decreases

Answer explanation

If KE is increasing, our PE must decrease for out total energy to be the same

Front

3 carts (A: 1 kg, B: 2 kg, C: 3 kg) at 20 m height. Which has highest KE when falling?

Back

Cart C

Answer explanation

The one that has the most PE in the beginning will have the most KE in the end

Front

There are 3 carts. Cart A is 1 kg, Cart B is 2 kg, and Cart C is 3 kg. If they are all at a height of 20 m, which cart will have the most PE?

Back

Cart C

Answer explanation

PE is based on height and mass

Front

A block is sliding across a table. If the block is losing kinetic energy, what type of force is acting on it?

Back

Non-conservative

Answer explanation

if you lose energy, then energy is not conserved. The only force we know that does that is friction

Front

At which point on a rollercoaster will you have the highest PE?

Back

The top

Answer explanation

PE is based on the HEIGHT and the mass

Front

At which point on a rollercoaster will you have the highest KE?

Back

The bottom

Answer explanation

KE and PE are inverse. KE is highest when PE is the lowest (at the bottom)

Front

Imagine you are on a rollercoaster doing firsthand experiments with energy. What has to be true for energy to be conserved?

Back

No friction

Answer explanation

Friction is the only thing that takes away our energy