Motion Equations

Front

Why does a car accelerate when going around a corner at 20 mph?

Back

The car is accelerating because it's changing direction.

Answer explanation

The car is accelerating because it's changing direction. Acceleration is not just about speed; it also involves changes in velocity, which includes direction. Thus, even at a constant speed of 20 mph, turning means the car accelerates.

Front

An airplane accelerates down a runway at 5.3 m/s² for 30.4s until it finally lifts off the ground. Determine the distance traveled before takeoff:

Back

2449m

Answer explanation

To find the distance traveled before takeoff, use the formula: distance = 0.5 * acceleration * time^2. Plugging in the values: distance = 0.5 * 5.3 m/s² * (30.4 s)² = 2449 m. Thus, the correct answer is 2449m.

Front

The graph represents the motion of a train travelling between two stations. Which statement about the train is correct? Options: Its acceleration takes a longer time than its deceleration, It travels at constant speed for less than half of its journey time, It travels 2000 m in the first 100 s, It travels 10 000 m at constant speed.

Back

It travels at constant speed for less than half of its journey time.

Answer explanation

The correct statement is that the train travels at constant speed for less than half of its journey time, indicating that most of the journey involves acceleration and deceleration phases.

Front

This is a velocity-time graph.  What is the object doing in segment A?

Back

Positive acceleration

Answer explanation

In segment A of the velocity-time graph, the velocity is increasing, indicating that the object is gaining speed. This means the object is experiencing positive acceleration.

Front

Calculate the acceleration for segment A.

Back

2 m/s²

Answer explanation

To find the acceleration for segment A, we use the formula a = (final velocity - initial velocity) / time. Given the values, the calculation yields 2 m/s², making this the correct choice.

Front

How far will a car move in 5 seconds if it started from rest and accelerates uniformly at 2.5 ms^-2?

Back

31.25 m

Answer explanation

Using the formula for distance under uniform acceleration, d = 0.5 * a * t^2, where a = 2.5 m/s² and t = 5 s, we get d = 0.5 * 2.5 * 25 = 31.25 m. Thus, the car moves 31.25 m.

Front

If a car is traveling forward at 15 m/s, how fast will it be going in 1.2 seconds if the acceleration is -10 m/s²?

Back

3 m/s

Front

A car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car’s acceleration?

Back

6 m/s²

Answer explanation

To find acceleration, use the formula: acceleration = (final velocity - initial velocity) / time. Here, initial velocity is 0 m/s, final velocity is 42 m/s, and time is 7 s. Thus, acceleration = (42 - 0) / 7 = 6 m/s².

Front

A car accelerates at 2 m/s². Assuming the car starts from rest, how much time does it need to accelerate to a speed of 16 m/s?

Back

8 s

Answer explanation

To find the time, use the formula: final speed = initial speed + (acceleration × time). Here, 16 m/s = 0 + (2 m/s² × time). Solving for time gives time = 16 m/s ÷ 2 m/s² = 8 s. Thus, the correct answer is 8 s.

Front

A car is traveling at 21.0 m/s and slows to a stop at a constant rate over 5.00 s. How far does the car travel during those 5.00 seconds before it stops?

Back

52.5 m

Answer explanation

To find the distance, use the formula: distance = initial velocity × time + 0.5 × acceleration × time². The car decelerates from 21.0 m/s to 0 m/s in 5.00 s, giving an average speed of 10.5 m/s. Thus, distance = 10.5 m/s × 5.00 s = 52.5 m.