Question

A bullet is fired into wood. The bullet penetrates for 7s to come to rest. Find the distance
travelled by the bullet in the wood if the retardation offered by the wood is 0.4m/s
1) 2.8m
2) 6.8m
3) 5.6m
4) 9.8m​

Answer 1

Answer:

9.8 m

Explanation:

This questions can be answered in two steps.

STEP 1 : (Finding the value of u)

v = u + at            [first equation of motion]

Here,

v = 0                  [ as it is given that it comes to the state of rest]

a = -0.4 m/s

t = 7 seconds        

On putting the values,

0 = u + (-0.4 x 7)

0 = u + (-2.8)

So, u = 2.8 m/s

STEP 2 : (Finding the distance)

s = ut + 1/2 at square

s = (2.8 x 7) + { 1/2 x (-0.4) x 7 square }

s = 19.6 + { (-0.4 x 49) / 2}

s = 19.6 + (-19.6/2)

s = 19.6 + (-9.8)

s = 19.6 - 9.8 = 9.8

Therefore, DISTANCE = 9.8 m