how to solve this question
Answers
Mass of bullet (m)= 20 g = 0.02 kg
Initial velocity of bullet (u) =100 m/s
Final velocity of bullet (V) = 0
Time (t)= 0.05 seconds
Acceleration on the bullet (a)?
Force acting on wooden block (F) = ?
Distance penetrated by bullet (s) = ?
We know;
Step 1: Calculate the acceleration of the v = u + at
0= 100+ a ×0.05
– a × 0.05 = 100
a = -2000 ms-2
Step 2: Calculate the distance of penetration using s = ut + ½ at2
= 100 × 0.05 + 0.5 x (–2000) × (0.05)2
= 7.5 m
We know, F = ma
Force acting on bullet (F)
= 0.02 × (– 2000) = -40N
Negative sign denotes that wooden block exerts force in the direction, opposite to the direction of motion of the bullet.
Given:
mass of the bullet (m) = 0.02 kg
initial velocity of the bullet (u) = 200 m/s
final velocity of the bullet (v) = 0 m/s
distance traversed by the bullet in the sand before coming to rest (S) = 0.03 m
From the equation of motion,
v
2
–u
2
=2aS
⇒0−200
2
=2aS
⇒a=−
3
2
×10
6
(Here a is the deceleration)
Hence the force exerted by the sand on the bullet is
F=m(−a)
⇒F=0.02×
3
2
×10
6
⇒F=13.3×10
3
N
Note: 1N=10
5
dyne
⇒F=13.3×10
8
dyne