Stemscopes Exam STEMscopes Forces and Motion 1 — Questions and Answers
Question 1: A soccer ball is rolling across a flat field and gradually slows to a stop. Which force is primarily responsible for slowing the ball?
- Gravity
- Friction (Correct answer)
- Applied force
- Normal force
Correct answer: Friction
Friction between the ball and the ground surface opposes the ball's motion and causes it to slow down and stop.
Question 2: According to Newton's First Law of Motion, an object at rest will remain at rest unless acted upon by a(n):
- Equal and opposite force
- Unbalanced (net) force (Correct answer)
- Gravitational force only
- Frictional force
Correct answer: Unbalanced (net) force
Newton's First Law states that an object maintains its state of rest or uniform motion unless an unbalanced (net) external force acts on it.
Question 3: A student pushes a 10 kg box with a net force of 20 N. What is the acceleration of the box?
- 0.5 m/s²
- 2 m/s² (Correct answer)
- 10 m/s²
- 200 m/s²
Correct answer: 2 m/s²
Using Newton's Second Law (F = ma), acceleration = F/m = 20 N ÷ 10 kg = 2 m/s².
Question 4: When a swimmer pushes off the pool wall, they move forward. This is an example of Newton's:
- First Law
- Second Law
- Third Law (Correct answer)
- Law of Gravitation
Correct answer: Third Law
Newton's Third Law states that for every action there is an equal and opposite reaction; the swimmer pushes the wall (action) and the wall pushes the swimmer forward (reaction).
Question 5: Which of the following is the best unit for measuring force in the SI system?
- Kilogram (kg)
- Newton (N) (Correct answer)
- Meter per second (m/s)
- Joule (J)
Correct answer: Newton (N)
The Newton (N) is the SI unit of force, defined as the force needed to accelerate 1 kg at 1 m/s².
Question 6: Two forces of 15 N and 10 N act in the same direction on an object. What is the net force?
- 5 N
- 10 N
- 15 N
- 25 N (Correct answer)
Correct answer: 25 N
When forces act in the same direction, they are added together: 15 N + 10 N = 25 N net force.
Question 7: A car traveling at a constant speed on a straight road has forces that are:
- Unbalanced, with a net forward force
- Balanced, with a net force of zero (Correct answer)
- Only gravitational forces acting
- Only frictional forces acting
Correct answer: Balanced, with a net force of zero
Constant speed (no acceleration) means the net force is zero, indicating all forces acting on the car are balanced.
Stemscopes Exam STEMscopes Forces and Motion 1
A soccer ball is rolling across a flat field and gradually slows to a stop.
Which force is primarily responsible for slowing the ball?