Newton's Laws, Momentum and Friction – Free

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Newton's Laws, Momentum and Friction

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Newton's Laws, Momentum and Friction

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Newton's first law of motion is also known as the law of:

laws-of-force-and-motion — Answer Key & Explanations (20 Questions)

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Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

Q1.Newton's first law of motion is also known as the law of:
- A.momentum
- B.acceleration
- C.inertia✓ Correct Answer
- D.gravitation
Explanation: The first law says a body stays at rest or in uniform motion unless acted on by a net force, which is the property of inertia.
Q2.The SI unit of force is the:
- A.joule
- B.watt
- C.pascal
- D.newton✓ Correct Answer
Explanation: One newton is the force that gives a 1 kg mass an acceleration of 1 m/s².
Q3.A passenger lurches forward when a moving bus stops suddenly. This is explained by:
- A.the gravity of the Earth
- B.inertia of motion✓ Correct Answer
- C.centripetal force
- D.buoyancy
Explanation: The passenger's body tends to keep moving forward while the bus stops, which is inertia of motion.
Q4.The product of the mass and the velocity of a body is called its:
- A.force
- B.power
- C.impulse
- D.momentum✓ Correct Answer
Explanation: Momentum p = m × v. It is a vector quantity.
Q5.The recoil of a gun when a bullet is fired is an example of Newton's:
- A.third law of motion✓ Correct Answer
- B.first law of motion
- C.second law of motion
- D.law of gravitation
Explanation: The bullet moves forward and the gun gets an equal and opposite push backwards: action and reaction.
Q6.F = ma is the mathematical form of Newton's:
- A.first law of motion
- B.second law of motion✓ Correct Answer
- C.third law of motion
- D.law of gravitation
Explanation: The second law states that the net force equals mass times acceleration.
Q7.The SI unit of momentum is:
- A.kg·m/s²
- B.kg·m²/s²
- C.N·m
- D.kg·m/s✓ Correct Answer
Explanation: Momentum is mass (kg) times velocity (m/s), so its unit is kg·m/s.
Q8.A force of 10 N acts on a body of mass 2 kg. The acceleration produced is:
- A.2 m/s²
- B.5 m/s²✓ Correct Answer
- C.8 m/s²
- D.20 m/s²
Explanation: a = F/m = 10 / 2 = 5 m/s².
Q9.The impulse of a force acting on a body equals the change in the body's:
- A.kinetic energy
- B.velocity
- C.momentum✓ Correct Answer
- D.mass
Explanation: Impulse = force × time = change in momentum.
Q10.The force of friction acts:
- A.in the same direction as the motion
- B.perpendicular to the surfaces
- C.towards the centre of the Earth
- D.opposite to the relative motion between the surfaces✓ Correct Answer
Explanation: Friction opposes the relative motion, or the tendency of motion, between two surfaces in contact.
Q11.The inertia of a body depends on its:
- A.mass✓ Correct Answer
- B.shape
- C.speed
- D.volume
Explanation: Mass is the measure of inertia: a heavier body is harder to start or stop.
Q12.Compared with sliding friction, rolling friction is generally:
- A.more
- B.less✓ Correct Answer
- C.equal
- D.infinite
Explanation: Rolling reduces contact and deformation, which is why wheels and ball bearings reduce friction.
Q13.The action and reaction forces of Newton's third law act on:
- A.the same body
- B.neither body
- C.two different bodies✓ Correct Answer
- D.the ground only
Explanation: Action and reaction are equal and opposite but act on different bodies, so they never cancel each other.
Q14.A raindrop falling through air eventually reaches a constant speed called its:
- A.escape velocity
- B.orbital velocity
- C.terminal velocity✓ Correct Answer
- D.angular velocity
Explanation: At terminal velocity, air resistance balances the weight, so the net force and acceleration are zero.
Q15.The weight of a 10 kg body on the Earth, taking g = 10 m/s², is:
- A.10 N
- B.100 N✓ Correct Answer
- C.1 N
- D.1000 N
Explanation: Weight W = m × g = 10 × 10 = 100 N.
Q16.The total linear momentum of a system is conserved when the net external force on it is:
- A.at its maximum
- B.constant but non-zero
- C.equal to its weight
- D.zero✓ Correct Answer
Explanation: With no net external force the total momentum stays constant; this is the law of conservation of momentum.
Q17.A force acts on a 5 kg body at rest and gives it a speed of 4 m/s in 0.1 s. The average force is:
- A.20 N
- B.50 N
- C.200 N✓ Correct Answer
- D.400 N
Explanation: F = m × Δv / t = 5 × 4 / 0.1 = 200 N.
Q18.A gun of mass 2 kg fires a bullet of mass 20 g at 100 m/s. The recoil velocity of the gun is:
- A.1 m/s✓ Correct Answer
- B.0.1 m/s
- C.10 m/s
- D.100 m/s
Explanation: By conservation of momentum, 0.02 × 100 = 2 × v, so v = 1 m/s in the opposite direction.
Q19.In a lift moving upward with a uniform acceleration, the apparent weight of a person is:
- A.greater than the actual weight✓ Correct Answer
- B.less than the actual weight
- C.equal to the actual weight
- D.zero
Explanation: The floor must push up with R = m(g + a), which is larger than mg, so the person feels heavier.
Q20.The law of inertia was first formulated by:
- A.Galileo✓ Correct Answer
- B.Aristotle
- C.Kepler
- D.Archimedes
Explanation: Galileo recognised inertia from his experiments with inclined planes; Newton later stated it as his first law.

Newton's first law of motion is also known as the law of:

laws-of-force-and-motion — Answer Key & Explanations (20 Questions)

Show

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

Q1.Newton's first law of motion is also known as the law of:
- A.momentum
- B.acceleration
- C.inertia✓ Correct Answer
- D.gravitation
Explanation: The first law says a body stays at rest or in uniform motion unless acted on by a net force, which is the property of inertia.
Q2.The SI unit of force is the:
- A.joule
- B.watt
- C.pascal
- D.newton✓ Correct Answer
Explanation: One newton is the force that gives a 1 kg mass an acceleration of 1 m/s².
Q3.A passenger lurches forward when a moving bus stops suddenly. This is explained by:
- A.the gravity of the Earth
- B.inertia of motion✓ Correct Answer
- C.centripetal force
- D.buoyancy
Explanation: The passenger's body tends to keep moving forward while the bus stops, which is inertia of motion.
Q4.The product of the mass and the velocity of a body is called its:
- A.force
- B.power
- C.impulse
- D.momentum✓ Correct Answer
Explanation: Momentum p = m × v. It is a vector quantity.
Q5.The recoil of a gun when a bullet is fired is an example of Newton's:
- A.third law of motion✓ Correct Answer
- B.first law of motion
- C.second law of motion
- D.law of gravitation
Explanation: The bullet moves forward and the gun gets an equal and opposite push backwards: action and reaction.
Q6.F = ma is the mathematical form of Newton's:
- A.first law of motion
- B.second law of motion✓ Correct Answer
- C.third law of motion
- D.law of gravitation
Explanation: The second law states that the net force equals mass times acceleration.
Q7.The SI unit of momentum is:
- A.kg·m/s²
- B.kg·m²/s²
- C.N·m
- D.kg·m/s✓ Correct Answer
Explanation: Momentum is mass (kg) times velocity (m/s), so its unit is kg·m/s.
Q8.A force of 10 N acts on a body of mass 2 kg. The acceleration produced is:
- A.2 m/s²
- B.5 m/s²✓ Correct Answer
- C.8 m/s²
- D.20 m/s²
Explanation: a = F/m = 10 / 2 = 5 m/s².
Q9.The impulse of a force acting on a body equals the change in the body's:
- A.kinetic energy
- B.velocity
- C.momentum✓ Correct Answer
- D.mass
Explanation: Impulse = force × time = change in momentum.
Q10.The force of friction acts:
- A.in the same direction as the motion
- B.perpendicular to the surfaces
- C.towards the centre of the Earth
- D.opposite to the relative motion between the surfaces✓ Correct Answer
Explanation: Friction opposes the relative motion, or the tendency of motion, between two surfaces in contact.
Q11.The inertia of a body depends on its:
- A.mass✓ Correct Answer
- B.shape
- C.speed
- D.volume
Explanation: Mass is the measure of inertia: a heavier body is harder to start or stop.
Q12.Compared with sliding friction, rolling friction is generally:
- A.more
- B.less✓ Correct Answer
- C.equal
- D.infinite
Explanation: Rolling reduces contact and deformation, which is why wheels and ball bearings reduce friction.
Q13.The action and reaction forces of Newton's third law act on:
- A.the same body
- B.neither body
- C.two different bodies✓ Correct Answer
- D.the ground only
Explanation: Action and reaction are equal and opposite but act on different bodies, so they never cancel each other.
Q14.A raindrop falling through air eventually reaches a constant speed called its:
- A.escape velocity
- B.orbital velocity
- C.terminal velocity✓ Correct Answer
- D.angular velocity
Explanation: At terminal velocity, air resistance balances the weight, so the net force and acceleration are zero.
Q15.The weight of a 10 kg body on the Earth, taking g = 10 m/s², is:
- A.10 N
- B.100 N✓ Correct Answer
- C.1 N
- D.1000 N
Explanation: Weight W = m × g = 10 × 10 = 100 N.
Q16.The total linear momentum of a system is conserved when the net external force on it is:
- A.at its maximum
- B.constant but non-zero
- C.equal to its weight
- D.zero✓ Correct Answer
Explanation: With no net external force the total momentum stays constant; this is the law of conservation of momentum.
Q17.A force acts on a 5 kg body at rest and gives it a speed of 4 m/s in 0.1 s. The average force is:
- A.20 N
- B.50 N
- C.200 N✓ Correct Answer
- D.400 N
Explanation: F = m × Δv / t = 5 × 4 / 0.1 = 200 N.
Q18.A gun of mass 2 kg fires a bullet of mass 20 g at 100 m/s. The recoil velocity of the gun is:
- A.1 m/s✓ Correct Answer
- B.0.1 m/s
- C.10 m/s
- D.100 m/s
Explanation: By conservation of momentum, 0.02 × 100 = 2 × v, so v = 1 m/s in the opposite direction.
Q19.In a lift moving upward with a uniform acceleration, the apparent weight of a person is:
- A.greater than the actual weight✓ Correct Answer
- B.less than the actual weight
- C.equal to the actual weight
- D.zero
Explanation: The floor must push up with R = m(g + a), which is larger than mg, so the person feels heavier.
Q20.The law of inertia was first formulated by:
- A.Galileo✓ Correct Answer
- B.Aristotle
- C.Kepler
- D.Archimedes
Explanation: Galileo recognised inertia from his experiments with inclined planes; Newton later stated it as his first law.

Newton's first law of motion is also known as the law of:

laws-of-force-and-motion — Answer Key & Explanations (20 Questions)

Related General Physics topics

Newton's first law of motion is also known as the law of:

laws-of-force-and-motion — Answer Key & Explanations (20 Questions)

Related General Physics topics