Which of the following could not be a unit of speed?

A. km/h B. s/m

C. m/s D. mm s^-1

Which of the following can sometimes be ‘zero’ for a moving body?

(i) average velocity

(ii) distance travelled

(iii) average speed

(iv) displacement

A. only (i) B. (i) and (ii)

C. (i) and (iv) D. only (iv)

When a car driver travelling at a speed of 20 m/s applies brakes and brings the car to rest in 40 s, then retardation will be :

A. + 2 m/s²

B. -2 m/s²

C. - 0.5 m/s²

D. + 0.5 m/s²

One of the following is not a vector quantity. This one is :

A. displacement B. speed

C. acceleration D. velocity

Which of the following could not be a unit of acceleration?

A. km/s²

B. cm s²

C. km/s

D. m/ s²