arrow_backBack to Study Resources

Quiz Chapter 7: Energy and Power

10 questions · Form 3 Science Bab 7: Energy and Power

Question 1 of 10Score: 0

A sports car of mass $1000 kg$ travels at a constant velocity of $20 m s-1$. Find its kinetic energy.

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. A sports car of mass $1000 kg$ travels at a constant velocity of $20 m s-1$. Find its kinetic energy.

  1. 100,000 J
  2. 200,000 J
  3. 400,000 J
  4. 20,000 J
Show answer

Answer: B

$E_k = 12 m v2 = 12 × 1000 × (20)2 = 500 × 400 = 200,000 J$ (or $200 kJ$).

2. In which of the following scenarios is NO work done according to physics definition?

  1. Lifting a $5 kg$ box from the floor onto a table
  2. Pushing a heavy concrete wall without moving it
  3. Pulling a toy car across the floor
  4. Climbing up a flight of stairs
Show answer

Answer: B

Work requires displacement in the direction of applied force ($W = F × s$). Since displacement is zero ($s = 0$), no work is done.

3. If the speed ($v$) of a moving vehicle is DOUBLED, how does its kinetic energy change?

  1. Doubles (2x)
  2. Triples (3x)
  3. Quadruples (4x)
  4. Remains unchanged
Show answer

Answer: C

Since $E_k \propto v2$, doubling the velocity increases kinetic energy by $(2)2 = 4$ times.

4. What is the rate at which work is done or energy is transferred called?

  1. Force
  2. Power
  3. Inertia
  4. Momentum
Show answer

Answer: B

Power is defined as the rate of doing work ($P = Wt$).

5. What is the formula used to calculate the kinetic energy ($E_k$) of a moving object?

  1. $E_k = mgh$
  2. $E_k = 12 F x$
  3. $E_k = 12 m v2$
  4. $E_k = F × s$
Show answer

Answer: C

Kinetic energy of a mass $m$ moving at speed $v$ is given by $E_k = 12 m v2$.

6. A rubber bowstring is pulled back with an average force of $100 N$ by a distance of $0.4 m$. How much elastic potential energy is stored in the bowstring?

  1. 20 J
  2. 40 J
  3. 80 J
  4. 250 J
Show answer

Answer: A

$E_e = 12 F x = 12 × 100 N × 0.4 m = 20 J$.

7. A simple pendulum swings back and forth between points A, B, and C (where B is the lowest point). At which position is its kinetic energy at a MAXIMUM?

  1. At position A (highest left point)
  2. At position B (lowest central point)
  3. At position C (highest right point)
  4. At both A and C
Show answer

Answer: B

At the lowest position (B), gravitational potential energy is converted entirely into kinetic energy, reaching maximum speed.

8. A student weighing $450 N$ climbs a staircase of vertical height $4 m$ in $6 seconds$. What is the useful power generated by the student?

  1. 1800 W
  2. 300 W
  3. 112.5 W
  4. 675 W
Show answer

Answer: B

Work $W = F × s = 450 N × 4 m = 1800 J$. Power $P = 18006 = 300 W$.

9. Calculate the gravitational potential energy possessed by a $2 kg$ book rested on a shelf $3 m$ above the floor ($g = 10 m s-2$).

  1. 6 J
  2. 15 J
  3. 30 J
  4. 60 J
Show answer

Answer: D

Gravitational potential energy $E_p = mgh = 2 × 10 × 3 = 60 J$.

10. Using conservation of energy, calculate the velocity of a $0.5 kg$ ball dropped from a height of $5 m$ just before hitting the floor ($g = 10 m s-2$).

  1. $10 m s-1$
  2. $25 m s-1$
  3. $50 m s-1$
  4. $100 m s-1$
Show answer

Answer: A

$mgh = 12 m v2 arrow v = √2gh = √(2 × 10 × 5) = √100 = 10 m s-1$.

Sponsored