BMST - Basic Math and Science Newton's Laws of Motion Questions and Answers 2 — Questions and Answers
Question 1: Newton's First Law of Motion states that an object at rest stays at rest unless acted upon by:
- An unbalanced external force (Correct answer)
- Gravity only
- Friction only
- Its own internal energy
Correct answer: An unbalanced external force
The First Law (law of inertia) states objects maintain their state of motion unless an unbalanced force acts on them.
Newton's First Law states that an object will remain at rest or in uniform straight-line motion unless acted upon by a net (unbalanced) external force. This property is called inertia — the tendency of objects to resist changes in motion. A book on a table stays still until pushed; a ball rolling on a frictionless surface would roll forever. Both gravity and friction are external forces, but the law encompasses any unbalanced force.
Question 2: According to Newton's Second Law, what is the acceleration of a 5 kg object with a net force of 20 N?
- 4 m/s² (Correct answer)
- 100 m/s²
- 0.25 m/s²
- 25 m/s²
Correct answer: 4 m/s²
F = ma, so a = F/m = 20 N / 5 kg = 4 m/s².
Newton's Second Law states F = ma (force equals mass times acceleration). Rearranging for acceleration: a = F/m = 20 N / 5 kg = 4 m/s². This means the object accelerates at 4 meters per second squared. The greater the force, the greater the acceleration; the greater the mass, the less the acceleration for the same force.
Question 3: Newton's Third Law is best described as:
- For every action, there is an equal and opposite reaction (Correct answer)
- Objects in motion stay in motion
- Force equals mass times acceleration
- Heavy objects fall faster than light ones
Correct answer: For every action, there is an equal and opposite reaction
The Third Law states that forces always come in equal and opposite pairs.
Newton's Third Law states that when object A exerts a force on object B, object B simultaneously exerts an equal force in the opposite direction on object A. These are called action-reaction pairs. When you push a wall, the wall pushes back on you with equal force. When Earth pulls you down with gravity, you pull Earth up with equal force. The forces act on different objects.
Question 4: A 10 kg box is pushed with 50 N of force on a frictionless surface. What is the acceleration?
- 5 m/s² (Correct answer)
- 500 m/s²
- 0.2 m/s²
- 40 m/s²
Correct answer: 5 m/s²
a = F/m = 50 N / 10 kg = 5 m/s².
On a frictionless surface, the applied force equals the net force. Using Newton's Second Law: a = F/m = 50 N / 10 kg = 5 m/s². The box accelerates at 5 m/s². If there were friction (say 10 N), the net force would be 50 - 10 = 40 N, and the acceleration would be 40/10 = 4 m/s². Friction reduces the net force and thus the acceleration.
Question 5: What is inertia?
- The tendency of an object to resist changes in its state of motion (Correct answer)
- The force that pulls objects toward Earth
- The energy stored in a spring
- The speed of an object
Correct answer: The tendency of an object to resist changes in its state of motion
Inertia is the resistance to changes in motion; it depends on mass — more mass means more inertia.
Inertia is the property of matter that causes it to resist changes in its state of motion (rest or uniform motion). Mass is the quantitative measure of inertia — a more massive object has greater inertia and requires more force to accelerate. A bowling ball is harder to start moving (and harder to stop) than a tennis ball because it has more inertia. Inertia is the concept behind Newton's First Law.
Question 6: A car and a truck collide. According to Newton's Third Law, which experiences a greater force?
- Both experience the same force (Correct answer)
- The car experiences greater force
- The truck experiences greater force
- Neither experiences any force
Correct answer: Both experience the same force
Newton's Third Law guarantees equal forces on both vehicles, though the smaller car accelerates more.
Newton's Third Law states that the forces are equal and opposite. The car pushes on the truck with the same force that the truck pushes on the car. However, since F = ma, the car (smaller mass) experiences greater acceleration (deceleration), which is why the car sustains more damage. The forces are equal; the effects differ because the masses differ.
BMST - Basic Math and Science Newton's Laws of Motion Questions and Answers 2
Newton's First Law of Motion states that an object at rest stays at rest unless acted upon by: