Question

4 two blocks of equal mass begin at the same height and slide down ramps of different materials and different angles. the graph below shows the energy distributions at a certain time. which statement is correct?
ramp 2 is steeper
the block on ramp 2 is moving faster than the block on ramp 1
the block on ramp 1 will reach the bottom first
the block on ramp 2 will have greater velocity at the bottom of the ramp than the block on ramp 1 will
5 a student places a rectangular rubber eraser on a leather - bound book, and begins to tilt the book. if the coefficient of friction between leather and rubber is 0.61, at what angle will the eraser first start to slide?

Explanation:

Step1: Analyze energy - conservation principle

In the absence of non - conservative forces (friction), all of the initial potential energy ($PE$) is converted into kinetic energy ($KE$) at the bottom of the ramp. But when friction is present, some of the initial $PE$ is lost as heat or other forms of energy.

Step2: Examine the graph

For Ramp 1, a larger percentage of the initial $PE$ is converted into $KE$ compared to Ramp 2, and less energy is lost. For Ramp 2, a significant amount of energy is lost, which indicates the presence of friction.

Step3: Evaluate each option

• Option 1: Only Ramp 2 has friction - This is consistent with the graph as there is energy loss only for Ramp 2.
• Option 2: Ramp 2 is steeper - There is no information in the graph to suggest the steepness of the ramps.
• Option 3: The block on Ramp 2 is moving faster than the block on Ramp 1 - Since more energy is lost in Ramp 2 due to friction, the block on Ramp 2 will have less $KE$ and thus be moving slower.
• Option 4: The block on Ramp 1 will reach the bottom first - There is no information about the time - of - travel in the graph.
• Option 5: The block on Ramp 2 will have greater velocity at the bottom of the ramp than the block on Ramp 1 - Since more energy is lost in Ramp 2, it will have less $KE$ and a lower velocity at the bottom.

Answer:

Only Ramp 2 has friction.