You are told 3 things...1. That there are two objects with equal masses. 2. Both objects are in motion. 3. One object has a greater kinetic energy than the other. How is this possible? (1 point)

Question

Responses

One object is blue and one object is red.
One object is blue and one object is red.

One object has a greater density then the other object.
One object has a greater density then the other object.

One object has a greater volume than the other object.
One object has a greater volume than the other object.

One object has a greater speed than the other object.
One object has a greater speed than the other object.

Answer 1

The correct response is:

One object has a greater speed than the other object.

Kinetic energy is given by the formula \( KE = \frac{1}{2}mv^2 \), where \( m \) is mass and \( v \) is velocity. Since both objects have equal masses, the object with the greater speed will have greater kinetic energy.

Answer 2

A large truck and a small car are moving at the same speed, traveling up and down hills, and over bumpy roads. Which one has more kinetic energy?(1 point)
Responses

The car has more kinetic energy because it moves fast down hills.
The car has more kinetic energy because it moves fast down hills.

The truck has more kinetic energy because it has a greater mass.
The truck has more kinetic energy because it has a greater mass.

The truck has less kinetic energy because it has greater mass.
The truck has less kinetic energy because it has greater mass.

The car and truck have the same kinetic energy

Answer 3

The correct response is:

The truck has more kinetic energy because it has a greater mass.

Kinetic energy is given by the formula \( KE = \frac{1}{2}mv^2 \). Since the truck has a greater mass than the car and they are moving at the same speed, the truck will have more kinetic energy.

Answer 4

Which object has the greatest kinetic energy?(1 point)
Responses

a red car mass of 500 kg moving at 3 m/s
a red car mass of 500 kg moving at 3 m/s

a green car with a mass of 500kg moving at 21 m/s
a green car with a mass of 500kg moving at 21 m/s

a yellow car with a mass of 500 kg moving at 12 m/s
a yellow car with a mass of 500 kg moving at 12 m/s

a blue car with a mass of 500 kg moving at 30 m/s

Answer 5

To determine which object has the greatest kinetic energy, we can use the kinetic energy formula:

\[ KE = \frac{1}{2}mv^2 \]

Since all cars have the same mass (500 kg), we can compare their kinetic energies based solely on their speeds.

1. Red car:
   \( KE = \frac{1}{2} \times 500 \times (3)^2 = \frac{1}{2} \times 500 \times 9 = 2250 , \text{J} \)

2. Green car:
   \( KE = \frac{1}{2} \times 500 \times (21)^2 = \frac{1}{2} \times 500 \times 441 = 110250 , \text{J} \)

3. Yellow car:
   \( KE = \frac{1}{2} \times 500 \times (12)^2 = \frac{1}{2} \times 500 \times 144 = 36000 , \text{J} \)

4. Blue car:
   \( KE = \frac{1}{2} \times 500 \times (30)^2 = \frac{1}{2} \times 500 \times 900 = 112500 , \text{J} \)

From these calculations:

• Red car: 2250 J
• Green car: 110250 J
• Yellow car: 36000 J
• Blue car: 112500 J

The blue car with a mass of 500 kg moving at 30 m/s has the greatest kinetic energy.

Answer 6

A skydiver jumps out of a plane and begins to accelerate. His speed increases to 20 m/s, then 30 m/s. His acceleration slows until he reaches a constant speed of 50 m/s. Which statement accurately describes his kinetic energy while falling?(1 point)
Responses

His kinetic energy increased while his speed increases, then it became constant.
His kinetic energy increased while his speed increases, then it became constant.

His kinetic energy was positive at first, but it decreased to zero when he stopped accelerating.
His kinetic energy was positive at first, but it decreased to zero when he stopped accelerating.

His kinetic energy increased quickly at first, then it increased at a constant rate.
His kinetic energy increased quickly at first, then it increased at a constant rate.

His kinetic energy would remain the same for the whole fall as long as he lost no mass.

Answer 7

The correct response is:

His kinetic energy increased while his speed increased, then it became constant.

As the skydiver accelerates and his speed increases from 20 m/s to 30 m/s, his kinetic energy also increases because kinetic energy is directly related to the square of the velocity (\( KE = \frac{1}{2}mv^2 \)). Once he reaches a constant speed of 50 m/s (assuming he reaches terminal velocity), his kinetic energy remains constant thereafter, as long as no external forces affect his speed and he does not lose any mass.