Question

An astronaut on the moon drops a rock from rest. The rock falls 0.8m in one second of falling time. If the dropped rock fell for a total of two seconds of time instead of 1 second, then the distance traveled would be:____.
A) The same.
B) Doubled.
C) Tripled.
D) Quadruple.
E) None of the above.

Answer 1

Answer:

D) Quadruple.

Explanation:

We will use the second equation of motion to solve this problem:

$s = v_it + \frac{1}{2}gt^2$

where,

s = distance travelled by the rock

vi = initial speed of rock = 0 m/s

t = time taken

g = acceleration due to gravity on the surface of the moon

Therefore,

$s = (0\ m/s)t+\frac{1}{2}gt^2\\\\s =\frac{1}{2}gt^2$----------- equation (1)

Now, we double the time:

$s' = \frac{1}{2}g(2t)^2\\\\s' = 4(\frac{1}{2}gt^2)$

using equation (1):

s' = 4s

Hence, the correct option is:

D) Quadruple.