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)

Question

Responses
chose 1
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 car and truck have the same kinetic energy.
The car and truck have the same kinetic energy.

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

Answer 1

The correct response is:

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

Kinetic energy is calculated using the formula \( KE = \frac{1}{2}mv^2 \), where \( m \) is mass and \( v \) is velocity. Since both the truck and car are moving at the same speed, the one with the greater mass (the truck) will have more kinetic energy.

Answer 2

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

Answer 3

bot?

Answer 4

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

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

Given that all the cars have the same mass (500 kg), we just need to calculate the kinetic energy for each car based on its velocity:

1. Red car (3 m/s): \[ KE = \frac{1}{2} \times 500 \text{ kg} \times (3 \text{ m/s})^2 = \frac{1}{2} \times 500 \times 9 = 2250 \text{ J} \]

2. Yellow car (12 m/s): \[ KE = \frac{1}{2} \times 500 \text{ kg} \times (12 \text{ m/s})^2 = \frac{1}{2} \times 500 \times 144 = 36000 \text{ J} \]

3. Green car (21 m/s): \[ KE = \frac{1}{2} \times 500 \text{ kg} \times (21 \text{ m/s})^2 = \frac{1}{2} \times 500 \times 441 = 110250 \text{ J} \]

4. Blue car (30 m/s): \[ KE = \frac{1}{2} \times 500 \text{ kg} \times (30 \text{ m/s})^2 = \frac{1}{2} \times 500 \times 900 = 112500 \text{ J} \]

Comparing all the kinetic energies, we find:

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

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

Answer 5

A wildlife keeper is trying to catch an escaping rabbit. Who has the greater kinetic energy, the rabbit or the wildlife keeper?

(1 point)
Responses

The rabbit because it has less mass.
The rabbit because it has less mass.

The wildlife keeper because they have a greater mass.
The wildlife keeper because they have a greater mass.

The wildlife keeper because they speed up and catch the rabbit.
The wildlife keeper because they speed up and catch the rabbit.

Neither one because they are moving at the same speed.

Answer 6

To determine who has greater kinetic energy, we need to consider the formula for kinetic energy:

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

Where \( m \) is the mass and \( v \) is the speed of the object.

Without specific values for the mass and speed of both the rabbit and the wildlife keeper, we can analyze the options:

1. If the rabbit is light but moving fast, it might have higher kinetic energy than the wildlife keeper if the keeper is much heavier but moving slowly.
2. Conversely, the wildlife keeper might have greater kinetic energy if they are significantly heavier or are running faster than the rabbit.

Given only the qualitative information:

• The rabbit has less mass: This does not directly determine kinetic energy since speed needs to be considered.
• The wildlife keeper has greater mass: This suggests that the keeper could have greater kinetic energy if they are moving at a comparable speed to the rabbit.
• The wildlife keeper speeds up to catch the rabbit: This indicates that they might increase their kinetic energy as they accelerate.
• Neither moves at the same speed: This depends on circumstances; if they are both moving at the same speed, the mass will play a crucial role.

Given this reasoning, the most reasonable option generally would be:

The wildlife keeper because they have a greater mass.

However, without knowing their exact speeds, this cannot be definitively stated. If the speeds were equal, then the wildlife keeper would likely have greater kinetic energy due to greater mass. If the rabbit is moving much faster, it could have greater kinetic energy despite its lower mass.

Answer 7

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

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

Answer 8

To analyze the skydiver's kinetic energy during his fall, we use the kinetic energy formula:

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

Where \( m \) is the mass of the skydiver and \( v \) is his velocity.

As the skydiver accelerates:

1. From rest to 20 m/s: His speed increases, so the kinetic energy increases.
2. From 20 m/s to 30 m/s: His speed continues to increase, leading to further increases in kinetic energy.
3. When he reaches a constant speed of 50 m/s: His kinetic energy becomes constant as long as his speed remains constant.

Given this sequence of events, the most accurate statement is:

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

This choice correctly reflects that the kinetic energy increases as the speed increases and then remains constant once the skydiver reaches a steady speed.