Speed & Velocity — Homi Bhabha Class 9 Physics MCQs with Solutions
Free Homi Bhabha Class 9 Physics Speed & Velocity MCQs with step-by-step solutions (10 questions). Part of Motion & Kinematics. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Speed & Velocity · medium · numerical
A car moving at 72 km/h has a speed in m/s of:
A. 72 m/s
B. 25 m/s
C. 20 m/s ✓ Correct
D. 200 m/s
Solution: Multiply by $\tfrac{5}{18}$: $72 \times \tfrac{5}{18} = 20$ m/s.
Q2 — Speed & Velocity · hard · numerical
A car covers the first half of a distance at 30 km/h and the second half at 60 km/h. Its average speed for the whole journey is:
A. 40 km/h ✓ Correct
B. 45 km/h
C. 50 km/h
D. 90 km/h
Solution: For equal distances, average speed $= \dfrac{2 \times 30 \times 60}{30 + 60} = 40$ km/h (45 km/h wrongly averages the speeds).
Q3 — Speed & Velocity · medium · numerical
A vehicle covers 60 km in 1.5 hours. Its average speed is:
A. 40 km/h ✓ Correct
B. 90 km/h
C. 30 km/h
D. 45 km/h
Solution: Average speed $= \dfrac{60}{1.5} = 40$ km/h.
Q4 — Speed & Velocity · medium · theory
A body is said to be moving with uniform velocity when it:
A. covers equal displacements in equal intervals of time along a straight line ✓ Correct
B. moves in a circle at constant speed
C. covers equal distances along any path
D. speeds up at a steady rate
Solution: Uniform velocity requires both constant speed AND unchanging direction, i.e. equal displacements in equal times in a straight line.
Q5 — Speed & Velocity · hard · theory
A body can have a constant speed but a changing velocity when it moves:
A. in a straight line at a steady rate
B. with increasing speed
C. and then stops
D. in a circular path at a steady rate ✓ Correct
Solution: In uniform circular motion the direction changes continuously, so velocity changes even though the speed is constant.
Q6 — Speed & Velocity · medium · numerical
A body travels 100 m in 4 s and the next 200 m in 6 s. Its average speed for the whole motion is:
A. 35 m/s
B. 30 m/s ✓ Correct
C. 50 m/s
D. 25 m/s
Solution: Average speed $= \dfrac{\text{total distance}}{\text{total time}} = \dfrac{300}{10} = 30$ m/s.
Q7 — Speed & Velocity · easy · theory
The rate of change of distance with time is called:
A. Speed ✓ Correct
B. Displacement
C. Acceleration
D. Velocity
Solution: Speed is the distance travelled per unit time. Velocity, in contrast, is the displacement per unit time and is a vector.
Q8 — Speed & Velocity · medium · numerical
A train covers 150 km in 2.5 hours. What is its average speed?
A. 375 km/h
B. 50 km/h
C. 75 km/h
D. 60 km/h ✓ Correct
Solution: Average speed = total distance divided by total time = 150 divided by 2.5 = 60 km/h.
Q9 — Speed & Velocity · hard · numerical
A car covers the first half of a journey at 40 km/h and the second half of equal distance at 60 km/h. What is its average speed for the whole journey?
A. 48 km/h ✓ Correct
B. 50 km/h
C. 100 km/h
D. 24 km/h
Solution: For two equal distances the average speed is the harmonic mean = (2 x 40 x 60) divided by (40 + 60) = 4800 divided by 100 = 48 km/h. The simple average of 50 km/h is the common mistake because more time is spent at the slower speed.
Q10 — Speed & Velocity · hard · theory
Assertion (A): A body can have constant speed and yet a changing velocity. Reason (R): Velocity is a vector, so a change of direction changes the velocity even if the magnitude stays the same. Choose the correct option.
A. Both A and R are true but R is not the correct explanation of A
B. Both A and R are true and R is the correct explanation of A ✓ Correct
C. A is true but R is false
D. A is false but R is true
Solution: A body in uniform circular motion moves at constant speed but its direction changes at every instant, so its velocity changes. This happens precisely because velocity is a vector, so R correctly explains A.