A 20 gram bullet moving with 200 m/s stops after penetrating a 2 cm of bone. Calculate the average force exerted by the bullet.

Asked by Topperlearning User | 4th Jun, 2014, 08:27: AM

Expert Answer:

Here we are given,
Mass of the bullet = 20 g = 20 × 10-3 kg
Initial velocity of the bullet is u = 200 m/s
Distance traveled = 2 cm = 2 × 10-2 m
Using 3rd equation of motion, we get
     
        straight v squared space equals space straight u squared space plus space 2 as
0 space equals space straight u squared space plus space 2 as
straight a space equals space fraction numerator minus straight u squared over denominator 2 straight s end fraction
      straight a space equals space fraction numerator minus 200 cross times 200 over denominator 2 cross times 2 cross times 10 to the power of minus 2 end exponent end fraction
straight a space equals space minus 10 to the power of 6 space straight m divided by straight s squared
      From Newton's second law, we have
      straight F space equals space ma
straight F space equals space 20 cross times 10 to the power of minus 3 end exponent cross times 10 to the power of 6
straight F space equals space 20 cross times 10 cubed space straight N
                                

Answered by  | 4th Jun, 2014, 10:27: AM