Question

A stone thrown vertically upwards from the surface of the moon at velocity of 24 m/sec. reaches a height of $s = 24t - 0.8t^{2}m$ after t sec. The acceleration due to gravity in m/sec² at the surface of the moon is

• A. 0.8
• B. 1.6
• C. 2.4
• D. 4.9

Answer 1

Answer: (B)

1.6

Answer 2

$\frac{ds}{dt} =$velocity = 24 = 24 – 1.6 t

So acceleration at $t,$ is $\left\lbrack \frac{d^{2}s}{dt^{2}} \right\rbrack = - 1.6$

As stone is thrown upwards, so acceleration due to gravity (which acts downwards) = 1.6.