,Question 1
A 2.5 kg object is lifted vertically through a height of 4.0 m.
The gravitational field strength is 9.8 N/kg.
What is the increase in gravitational potential energy?
A. 9.8 J
B. 24.5 J
C. 98 J
D. 245 J
Correct answer: D
Rationale:
Gravitational potential energy depends on mass, gravitational field strength and height.
2.5 × 9.8 × 4.0 = 98 J.
Correction: The calculation gives 98 J, so the correct answer is C, not D.
Question 2
A cyclist has a mass of 70 kg and travels at 6.0 m/s.
What is the cyclist's kinetic energy?
A. 210 J
B. 420 J
C. 1260 J
D. 2520 J
Correct answer: C
Rationale:
Kinetic energy = ½mv².
½ × 70 × 6² = 35 × 36 = 1260 J.
The important trap is forgetting to square the velocity.
Question 3
A car's speed is doubled while its mass remains constant.
,What happens to its kinetic energy?
A. It doubles.
B. It becomes four times greater.
C. It becomes half as large.
D. It becomes eight times greater.
Correct answer: B
Rationale:
Kinetic energy is proportional to velocity squared. Doubling velocity gives:
2² = 4.
Therefore, the kinetic energy becomes four times greater.
Question 4
Two objects have the same kinetic energy. Object X has twice the mass of object Y.
Which statement about their speeds is correct?
A. X travels twice as fast as Y.
B. X travels four times as fast as Y.
C. X travels at half the speed of Y.
D. X travels at 1/2 times the speed of Y.
Correct answer: D
Rationale:
Since KE = ½mv², keeping kinetic energy constant means:
mv² = constant.
If mass doubles, v² must halve.
, Therefore, speed becomes 1/√2 of the original speed.
Question 5
A 5.0 kg object is moving at 4.0 m/s.
How much kinetic energy does it have?
A. 10 J
B. 20 J
C. 40 J
D. 80 J
Correct answer: C
Rationale:
½ × 5.0 × 4.0²
= 2.5 × 16
= 40 J.
Question 6
A student says:
"An object has no energy because it is stationary."
Which response is correct?
A. Correct, because kinetic energy is zero.
B. Correct, because all energy depends on movement.
C. Incorrect, because the object may possess gravitational potential energy.
D. Incorrect, because stationary objects always have thermal energy only.
Correct answer: C
Rationale:
A stationary object can have zero kinetic energy but still possess other stores of energy, such
as gravitational potential energy, chemical energy or thermal energy.
Question 7
A ball is released from a height and falls without significant air resistance.
A 2.5 kg object is lifted vertically through a height of 4.0 m.
The gravitational field strength is 9.8 N/kg.
What is the increase in gravitational potential energy?
A. 9.8 J
B. 24.5 J
C. 98 J
D. 245 J
Correct answer: D
Rationale:
Gravitational potential energy depends on mass, gravitational field strength and height.
2.5 × 9.8 × 4.0 = 98 J.
Correction: The calculation gives 98 J, so the correct answer is C, not D.
Question 2
A cyclist has a mass of 70 kg and travels at 6.0 m/s.
What is the cyclist's kinetic energy?
A. 210 J
B. 420 J
C. 1260 J
D. 2520 J
Correct answer: C
Rationale:
Kinetic energy = ½mv².
½ × 70 × 6² = 35 × 36 = 1260 J.
The important trap is forgetting to square the velocity.
Question 3
A car's speed is doubled while its mass remains constant.
,What happens to its kinetic energy?
A. It doubles.
B. It becomes four times greater.
C. It becomes half as large.
D. It becomes eight times greater.
Correct answer: B
Rationale:
Kinetic energy is proportional to velocity squared. Doubling velocity gives:
2² = 4.
Therefore, the kinetic energy becomes four times greater.
Question 4
Two objects have the same kinetic energy. Object X has twice the mass of object Y.
Which statement about their speeds is correct?
A. X travels twice as fast as Y.
B. X travels four times as fast as Y.
C. X travels at half the speed of Y.
D. X travels at 1/2 times the speed of Y.
Correct answer: D
Rationale:
Since KE = ½mv², keeping kinetic energy constant means:
mv² = constant.
If mass doubles, v² must halve.
, Therefore, speed becomes 1/√2 of the original speed.
Question 5
A 5.0 kg object is moving at 4.0 m/s.
How much kinetic energy does it have?
A. 10 J
B. 20 J
C. 40 J
D. 80 J
Correct answer: C
Rationale:
½ × 5.0 × 4.0²
= 2.5 × 16
= 40 J.
Question 6
A student says:
"An object has no energy because it is stationary."
Which response is correct?
A. Correct, because kinetic energy is zero.
B. Correct, because all energy depends on movement.
C. Incorrect, because the object may possess gravitational potential energy.
D. Incorrect, because stationary objects always have thermal energy only.
Correct answer: C
Rationale:
A stationary object can have zero kinetic energy but still possess other stores of energy, such
as gravitational potential energy, chemical energy or thermal energy.
Question 7
A ball is released from a height and falls without significant air resistance.
