In Example 7.7, we calculated the final speed of a roller

Chapter 7, Problem 7

(choose chapter or problem)

QUESTION:

In Example 7.7, we calculated the final speed of a roller coaster that descended 20 m in height and had an initial speed of 5 m/s downhill. Suppose the roller coaster had had an initial speed of 5 m/s uphill instead, and it coasted uphill, stopped, and then rolled back down to a final point 20 m below the start. We would find in that case that it had the same final speed. Explain in terms of conservation of energy.

Example 7.7 Finding the Speed of a Roller Coaster from its Height

(a) What is the final speed of the roller coaster shown in Figure 7.8 if it starts from rest at the top of the 20.0 m hill and work done by frictional forces is negligible? (b) What is its final speed (again assuming negligible friction) if its initial speed is 5.00 m/s?

Questions & Answers

QUESTION:

Example 7.7 Finding the Speed of a Roller Coaster from its Height

ANSWER:

Step 1 of 2

Let's look into the figure,

We are assuming that the roller coaster had a initial velocity of as it moves upwards. As it moves upwards, the kinetic energy is decreasing and as it reaches the top of the hill, the kinetic energy of the roller coaster is zero and it has maximum potential energy.