Motion & Velocity
Acceleration
Forces in Action
Newton's Laws
Your questions
100
What do scientists call an object's change in position over time compared to a reference point?
Motion
100
True or False: An object must speed up to be accelerating.
False. Slowing down and changing direction are also acceleration.
100
What is the scientific definition of a force?
A push or pull acting on an object.
100
Which equation represents Newton's Second Law?
F = ma
100
What units should you use when calculating speed, acceleration, and force?
- Speed: m/s
- Acceleration: m/s²
- Force: Newtons (N)
200
A passenger is sitting on a moving train. Is the passenger moving relative to the train seat or the trees outside?
the trees outside.
200
A car travels around a curve without changing its speed. Is it accelerating?
Yes. Its direction changes, so its velocity changes.
200
Which is a non-contact force: friction, gravity, or air resistance?
gravity
200
If an object's mass stays the same but the net force doubles, what happens to its acceleration?
Its acceleration doubles.
200
What is the difference between mass and weight?
Mass is the amount of matter in an object, while weight is the force of gravity acting on that object.
300
Two airplanes travel at 600 km/h. One flies north, and the other flies south. Do they have the same velocity?
No. They have the same speed (600 km/h), but are moving in different directions, so their velocity is different.
300
A bicycle slows from 12 m/s to 4 m/s in 2 seconds. What is its average acceleration? Assume its initial direction is positive.
4-12 = -8
-8/2 = -4 m/s2
300
A student pushes a box to the right with 50 N of force. Friction pushes left with 20 N. What is the net force?
30 N right
300
Two identical toy cars experience the same net force. One car carries extra weights. Which car will accelerate faster?
The car without extra weights because it has less mass.
300
A book is resting on a table. Gravity pulls the book downward, but the table pushes upward.
Are the forces balanced or unbalanced? How do you know?
Balanced. The upward force from the table equals the downward gravitational force, so the net force is zero.
400
A swimmer travels 80 meters in 20 seconds. What is the swimmer's average speed?
speed = distance/time
speed = 80/20
speed = 4 m/s
400
A position-time graph shows a straight line that slopes upward. What does this tell you about the object's motion?
Its position is increasing at a constant rate; it has a constant positive velocity.
400
Two students push a table in opposite directions with equal forces of 40 N. What is the net force? Are the forces balanced or unbalanced?
0 N; balanced forces.
400
A 10 kg object experiences a net force of 50 N. What is its acceleration?
force = mass x acceleration
force = acceleration
mass
50 N = acceleration
10 kg
5 m/s2= acceleration
400
A large truck and a small car collide.
A student says, "The truck hits the car with more force because the truck has more mass."
Is the student correct? Explain.
No. According to Newton's Third Law, the truck and car exert equal and opposite forces on each other during the collision.
However, the smaller car may experience greater acceleration because it has less mass.
500
A student walks 30 meters east in 10 seconds, then another 30 meters east in 5 seconds. During which part of the trip was the student's average speed greater? Explain using numbers.
The second part. The student traveled at 3 m/s during the first part (30 m/10 s) and 6 m/s during the second (30 m/5 s).
500
A soccer ball rolls across a grassy field and gradually slows down. What force causes it to slow, and in which direction does that force act?
Friction. It acts opposite the ball's motion.
500
A large elephant pushes against a small cart. The cart pushes back on the elephant. Which object exerts the greater force on the other? Explain.
Neither. According to Newton's Third Law, the force pairs are equal in magnitude and opposite in direction.
- The elephant pushes forward on the cart.
- The cart pushes backward on the elephant with an equal amount of force.
- These forces act on different objects, so they do not cancel each other out.
500
A box has three horizontal forces acting on it:
- 20 N to the right
- 15 N to the left
- 10 N to the left
What is the net force? Which direction will the box accelerate?
Total force left = 15 + 10 = 25 N
Total force right = 20 N
Net force = 25 − 20 = 5 N left
The box will accelerate to the left.