Chapter 9, Problem 29A

The roller coaster ride starts with the car at rest at point A.

a. Rank from greatest to least the car’s speed at each point.

b. Rank from greatest to least the car’s kinetic energy at each point.

c. Rank from greatest to least the car’s potential energy at each point.

To determine

To Rank: Car's speed from greatest to least.

Answer to Problem 29A

  $\text{D>B> C> E> A}$

Explanation of Solution

Introduction:

Speed is how fast or how slow the object is moving. It is a scalar quantity.

At point A, the car is at height so its speed is zero. When car comes to point B, its potential energy gets converted to kinetic energy. So, it comes to position B with high speed. At point B, its speed is high. Again, car goes to point C so its speed decreases and then car speed increases at point D. At point E the car finally reaches certain height by gaining potential energy. The height of point Eis less than point A.

Conclusion:

The ranking of car's speed from greatest to least is D, B, C, E, A.

To determine

To Rank: Car’s kinetic energy from greatest to least.

Answer to Problem 29A

  $\text{D>B> C> E> A}$

Explanation of Solution

Introduction:

When an object is in motion, it possess the kinetic energy. Its SI unit is joules.

Kinetic energy of car depends on car's speed. As speed of car increases, kinetic energy increases. At high point car, has high potential energy and low kinetic energy. Here car's speed is high at point D and it decreases for point B, C, E, A.

Conclusion:

Ranking of car's kinetic energy from greatest to least is D, B, C, E, A.

To determine

To Rank:Car’s potential energy from greatest to least.

Answer to Problem 29A

  $\text{A> E> C> B > D}$

Explanation of Solution

Introduction:

Potential energy is the energy possessed by the object due to its position. Potential energy is high if object position is high and low if object’s position is low.

Potential energy of car is proportional to car's height. Potential energy will be high for high car's position and low for low position.

Here car's position is measured from ground will be from highest to lowest will be A, E, C, B and D.

Conclusion:

Ranking of car's potential energy from greatest to least is A, E, C, B and D.