Question

1. which would increase the kinetic energy of a wagon? select all that apply.

a) add mass to the wagon.
b) decrease the mass of the wagon.
c) increase the speed of the wagon.
d) decrease the speed of the wagon.

1. a dump truck, a sports car, and a bicycle are traveling at the same velocity. which is true?

a) they all have the same kinetic energy.
b) the sports car has the most kinetic energy.
c) the bicycle has the least kinetic energy.
d) more information is needed to compare their kinetic energy.

Explanation:

Question 4

The formula for kinetic energy is \( KE = \frac{1}{2}mv^2 \), where \( m \) is mass and \( v \) is speed.

Step 1: Analyze the effect of mass

From the formula, kinetic energy is directly proportional to mass (\( KE \propto m \)). So, increasing mass (adding mass to the wagon) will increase \( KE \), and decreasing mass will decrease \( KE \). Thus, option A is correct, B is incorrect.

Step 2: Analyze the effect of speed

Kinetic energy is also directly proportional to the square of speed (\( KE \propto v^2 \)). So, increasing speed will increase \( KE \), and decreasing speed will decrease \( KE \). Thus, option C is correct, D is incorrect.

Using the kinetic energy formula \( KE = \frac{1}{2}mv^2 \), when velocity (\( v \)) is the same, \( KE \) depends on mass (\( m \)). A dump truck has more mass than a sports car, which has more mass than a bicycle.

• Option A: False, as mass differs, \( KE \) differs.
• Option B: False, dump truck has more mass than sports car, so dump truck has more \( KE \).
• Option C: True, bicycle has the least mass, so least \( KE \) (since \( v \) is same).
• Option D: False, we know velocity is same, and can compare based on mass (even if exact masses aren't known, we know relative masses: dump truck > sports car > bicycle).

Answer:

A) Add mass to the wagon, C) Increase the speed of the wagon

Question 5