Acceleration

What is the unit of acceleration as described in the video?

• Meters per second

• Meters per second squared

• Kilometers per hour

• Seconds per meter

Answer explanation

The unit of acceleration is meters per second squared (m/s²), which indicates how much the velocity of an object changes per second. This distinguishes it from other options like meters per second or kilometers per hour.

If Moby's initial speed is 0 m/s and his final speed is 10 m/s over 2 seconds, what is his acceleration?

• 2 m/s²

• 5 m/s²

• 10 m/s²

• 20 m/s²

Answer explanation

Acceleration is calculated using the formula: (final speed - initial speed) / time. Here, (10 m/s - 0 m/s) / 2 s = 5 m/s². Thus, Moby's acceleration is 5 m/s².

Which of the following scenarios describes negative acceleration?

• Moby speeds up while going down a ramp.

• Moby maintains a constant speed.

• Moby slows down to a stop.

• Moby turns around while maintaining speed.

Answer explanation

Negative acceleration occurs when an object slows down. In this scenario, Moby slowing down to a stop indicates a decrease in speed, which is the definition of negative acceleration.

What is the formula for calculating acceleration as mentioned in the video?

Answer explanation

The correct formula for calculating acceleration is \( \text{Acceleration} = \frac{\text{Final Speed} - \text{Initial Speed}}{\text{Time}} \). This formula shows how much the speed changes over a specific time period.

If Moby's speedometer reads 10 m/s at the bottom of the ramp, what was his initial speed at the top of the ramp?

• 0 m/s

• 5 m/s

• 10 m/s

• 15 m/s

Answer explanation

Moby's speedometer reading 10 m/s at the bottom indicates he gained speed while descending the ramp. Assuming no initial speed at the top, the correct answer is 0 m/s.

How does the angle of the ramp affect Moby's acceleration?

• A steeper ramp decreases acceleration.

• A steeper ramp increases acceleration.

• The angle of the ramp does not affect acceleration.

• A steeper ramp maintains constant acceleration.

Answer explanation

A steeper ramp increases the component of gravitational force acting along the ramp, leading to greater acceleration. Therefore, Moby's acceleration increases as the ramp's angle becomes steeper.

What happens to Moby's speed when he hits the brakes on his skateboard?

• His speed increases.

• His speed remains constant.

• His speed decreases.

• His speed becomes zero instantly.

Answer explanation

When Moby hits the brakes on his skateboard, friction acts against his motion, causing his speed to decrease. Therefore, the correct answer is that his speed decreases.

If Moby's acceleration is 5 m/s², how much will his speed increase after 3 seconds?

• 5 m/s

• 10 m/s

• 15 m/s

• 20 m/s

Answer explanation

To find the increase in speed, use the formula: increase = acceleration × time. Here, increase = 5 m/s² × 3 s = 15 m/s. Thus, Moby's speed increases by 15 m/s after 3 seconds.

What is the effect of negative acceleration on Moby's skateboard?

• It speeds up the skateboard.

• It slows down the skateboard.

• It makes the skateboard turn.

• It has no effect on the skateboard.

Answer explanation

Negative acceleration, also known as deceleration, reduces the speed of an object. Therefore, in the context of Moby's skateboard, negative acceleration slows down the skateboard.

If Moby's initial speed is 0 m/s and his acceleration is 5 m/s², what will be his speed after 4 seconds?

• 5 m/s

• 10 m/s

• 15 m/s

• 20 m/s

Answer explanation

To find Moby's speed after 4 seconds, use the formula: final speed = initial speed + (acceleration × time). Here, final speed = 0 m/s + (5 m/s² × 4 s) = 20 m/s. Thus, the correct answer is 20 m/s.