Speed, Velocity, Acceleration and Projectile Motion

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

1. Q1.The rate of change of displacement is called:

   • A.acceleration
   • B.velocity✓ Correct Answer
   • C.momentum
   • D.force

   Explanation: Velocity = displacement / time.

2. Q2.The SI unit of acceleration is:

   • A.metre per second
   • B.newton
   • C.metre
   • D.metre per second squared✓ Correct Answer

   Explanation: Acceleration is the rate of change of velocity, in m/s².

3. Q3.In uniform circular motion, which quantity remains constant?

   • A.speed✓ Correct Answer
   • B.velocity
   • C.acceleration
   • D.displacement

   Explanation: Direction changes constantly, so velocity changes; speed does not.

4. Q4.The slope of a distance-time graph gives:

   • A.acceleration
   • B.speed✓ Correct Answer
   • C.displacement
   • D.force

   Explanation: Slope of distance over time is speed.

5. Q5.The acceleration due to gravity near the Earth's surface is about:

   • A.1.6 m/s²
   • B.98 m/s²
   • C.9.8 m/s²✓ Correct Answer
   • D.3.8 m/s²

   Explanation: All freely falling bodies share this acceleration in the absence of air.

6. Q6.The area under a velocity-time graph gives:

   • A.acceleration
   • B.speed
   • C.force
   • D.displacement✓ Correct Answer

   Explanation: Integrating velocity over time gives displacement.

7. Q7.In the equation v = u + at, the symbol u stands for:

   • A.final velocity
   • B.average speed
   • C.initial velocity✓ Correct Answer
   • D.uniform acceleration

   Explanation: u is the initial and v the final velocity.

8. Q8.A car moving at 20 m/s is brought to rest in 5 s. Its retardation is:

   • A.2 m/s²
   • B.4 m/s²✓ Correct Answer
   • C.5 m/s²
   • D.100 m/s²

   Explanation: a = (0 - 20) / 5 = -4 m/s².

9. Q9.A body starts from rest with acceleration 2 m/s². The distance covered in 5 s is:

   • A.10 m
   • B.50 m
   • C.20 m
   • D.25 m✓ Correct Answer

   Explanation: s = ½at² = ½ × 2 × 25 = 25 m.

10. Q10.In uniform circular motion the centripetal force acts:

    • A.away from the centre
    • B.along the tangent
    • C.towards the centre of the circle✓ Correct Answer
    • D.along the direction of velocity

    Explanation: It continually turns the velocity without changing speed.

11. Q11.The range of a projectile is maximum when the angle of projection is:

    • A.30°
    • B.60°
    • C.90°
    • D.45°✓ Correct Answer

    Explanation: Range is proportional to sin 2θ, which peaks at 45°.

12. Q12.The acceleration of a body moving with constant velocity is:

    • A.zero✓ Correct Answer
    • B.equal to g
    • C.constant and non-zero
    • D.increasing

    Explanation: No change in velocity means no acceleration.

13. Q13.A car travels 60 km in the first hour and 40 km in the second hour. Its average speed is:

    • A.40 km/h
    • B.60 km/h
    • C.50 km/h✓ Correct Answer
    • D.100 km/h

    Explanation: Total distance 100 km over 2 hours.

14. Q14.The displacement of a particle after one complete circle is:

    • A.zero✓ Correct Answer
    • B.the circumference
    • C.the diameter
    • D.the radius

    Explanation: It returns to the start, so displacement is zero though distance is not.

15. Q15.The SI unit of angular velocity is:

    • A.metre per second
    • B.radian per second✓ Correct Answer
    • C.hertz only
    • D.degree

    Explanation: Angular velocity is the angle turned per unit time.

16. Q16.The time period T and frequency f of circular motion are related by:

    • A.T = 1/f✓ Correct Answer
    • B.T = f
    • C.T = f²
    • D.T = 2f

    Explanation: Frequency is the reciprocal of the time period.

17. Q17.A ball thrown vertically upward at 20 m/s (take g = 10 m/s²) reaches its highest point after:

    • A.1 s
    • B.2 s✓ Correct Answer
    • C.4 s
    • D.0.5 s

    Explanation: t = u/g = 20/10 = 2 s.

18. Q18.At the highest point of a ball thrown vertically upward, its acceleration is:

    • A.zero
    • B.g, directed upward
    • C.g, directed downward✓ Correct Answer
    • D.infinite

    Explanation: Velocity is zero there, but gravity still acts.

19. Q19.A body thrown upward at 20 m/s (g = 10 m/s²) reaches a maximum height of:

    • A.10 m
    • B.40 m
    • C.5 m
    • D.20 m✓ Correct Answer

    Explanation: h = u²/2g = 400/20 = 20 m.

20. Q20.Two projectiles are thrown with the same speed at angles of 30° and 60°. Their ranges are:

    • A.equal✓ Correct Answer
    • B.greater for 30°
    • C.greater for 60°
    • D.zero for both

    Explanation: Complementary angles give the same range.