Motion in Action
Accelerate!
Newton Says
What if...?
100
Maya walks 40 meters in 10 seconds. What is her average speed?
4 m/s
100
A skateboarder speeds up while traveling straight ahead. Is the skateboarder accelerating?
Yes! The skateboarder is speeding up.
100
A 5 kg cart accelerates at 2 m/s². What is the force acting on the cart?
10 N
100
... you push the same cart with a greater net force. What happens to its acceleration?
Acceleration increases
200
Two runners both move at 6 m/s. One runs east and the other west. Do they have the same velocity? Explain.
No. Their directions are different.
200
A bicycle slows from 9 m/s to 4 m/s. Is the bicycle accelerating? Explain.
Yes. Slowing down is a change in velocity, so it is still accelerating.
200
A 4 kg object experiences a net force of 20 N. What is its acceleration?
5 m/s2
200
... two carts experience the same net force. One cart has more mass. Which cart accelerates more?
The one with less mass.
300
A dog runs 5 m/s north, turns around, and runs 5 m/s south. Its speed didn't change. Did its velocity change?
Yes, because it's direction changed.
300
A race car travels around a circular track at a constant 70 m/s. Why is it still accelerating?
It's direction is changing as it goes around the track.
300
A student measures these values in an investigation:
F = 18 N
m = 6 kg
a = 2 m/s2
Does this satisfy Newton's second law? Why or why not?
No because the values do not satisfy F = ma
18 does not equal 6 x 2
300
... you load several heavy books onto a cart but push it with the same net force as before. Predict what happens to its acceleration and explain why.
Acceleration decreases because its mass increased while force stays the same.
400
A biker biked 100 m at a constant 10 m/s. How long did it take them?
10 s.
400
What are the two ways that an object can accelerate?
Change in speed or change in direction
400
A student calculates the acceleration of a 5 kg cart pushed by a 15 N net force as 75 m/s². Explain the student's mistake and give the correct answer.
The student should have done force divided by mass, which gives 5 m/s2
400
... cart A has twice the mass of Cart B. You want both carts to have the same acceleration. How must the force on Cart A compare with the force on Cart B?
Force on Cart A should be twice that of Cart B's force
500
Car A travels 30 m in 5 s. Car B travels 42 m in 7 s. Which car has the greater average speed?
Neither. They have the same average speed.
500
The racetrack above shows three cars (A, B and C) going clockwise along the track. All cars are going at the same speed. Which car will accelerate first? Explain.
Car B will accelerate first because it will be the first to change its direction
500
Cart A has a mass of 2 kg and accelerates at 6 m/s². Cart B has a mass of 4 kg and accelerates at 3 m/s². Which experiences the greater net force?
Neither. Both are experiencing the same amount of force.
500
... a toy car's mass is doubled and the net force acting on it is doubled. What happens to its acceleration? Explain using F = ma.
The acceleration stays the same. Doubling both F and m keeps acceleration the same