APS - Motion

A vector is a quantity that has magnitude and no direction

• True

• False

Answer explanation

The statement is false because a vector is defined as a quantity that has both magnitude and direction, not just magnitude.

The rate of change in velocity; how quickly velocity is changing

• speed

• velocity

• resultant speed

• acceleration

Answer explanation

The rate of change in velocity is defined as acceleration. It measures how quickly an object's velocity changes over time, making 'acceleration' the correct choice among the options provided.

Tags

NGSS.HS-PS2-1

The unit for acceleration is

• m²/s

• m/s

• m/s²

• m/s³

Answer explanation

The unit for acceleration is derived from the change in velocity over time. Velocity is measured in meters per second (m/s), and since acceleration is the change in velocity per second, the correct unit is meters per second squared (m/s²).

Tags

NGSS.HS-PS2-1

If velocity and acceleration are in the same direction an object ____________.

• speeds up

• slows done

• stops

• turns

Answer explanation

When velocity and acceleration are in the same direction, the object's speed increases, meaning it speeds up. This is because acceleration adds to the velocity, resulting in a greater speed.

Tags

NGSS.HS-PS2-1

If velocity and acceleration are in the opposite direction, the object _________.

• stops

• none

• slows down

• speeds up

Answer explanation

When velocity and acceleration are in opposite directions, the object experiences a decrease in speed, meaning it slows down. Thus, the correct answer is 'slows down'.

Tags

NGSS.HS-PS2-1

Acceleration due to gravity is (a)   m/s/s.

Answer explanation

The acceleration due to gravity is approximately 9.8 m/s² on Earth. In many examples, rounding this value to 10 m/s/s is appropriate.

Tags

NGSS.HS-PS2-4

A car moving at 80 mph has a velocity of -35.8 m/s. What acceleration would it have if it took 5.0 s to come to a complete stop?

• 6.16 m/s/s

• -3.12 m/s/s

• 7.16 m/s/s

• -7.16 m/s/s

Answer explanation

To find acceleration, use the formula a = (final velocity - initial velocity) / time. The initial velocity is -35.8 m/s, final velocity is 0 m/s, and time is 5.0 s. This gives a = (0 - (-35.8)) / 5 = 7.16 m/s².

Tags

NGSS.HS-PS2-1

If a ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 50 m/s² for 3 seconds, what will its final velocity be?

• 170 m/s

• 140 m/s

• 150 m/s

• 160 m/s

Answer explanation

To find the final velocity, use the formula: final velocity = initial velocity + (acceleration × time). Here, final velocity = 10 m/s + (50 m/s² × 3 s) = 10 m/s + 150 m/s = 160 m/s. Thus, the correct answer is 160 m/s.

Tags

NGSS.HS-PS2-1

An object falls from a building. How long will it take before it reaches a speed of 50 m/s?

• 5s

• -5s

• 4s

• -4s

Answer explanation

Using the formula v = g * t, where g = 9.8 m/s², we can find the time. Setting v = 50 m/s gives t = 50 / 9.8 ≈ 5.1s. Rounding down, it takes approximately 5 seconds to reach that speed, making 5s the correct answer.

Tags

NGSS.HS-PS2-1

What is the acceleration of a car that travels in a straight line at a constant speed?

• 0 m/s/s

• 9.8 m/s/s

• 4 m/s/s

• 2 m/s/s

Answer explanation

The acceleration of an object is defined as the rate of change of its velocity. Since the car is traveling at a constant speed in a straight line, its velocity is not changing, resulting in an acceleration of 0 m/s/s.

Tags

NGSS.HS-PS2-1