Question

If a 10g bullet enters a tree trunk with a specd of 400m/s and
exits it with just 1% of the initial kinetic energy. Then the work
done by the bullet on the trunk is equal to​

Answer 1

Answer:

Final KE = 792 J = 0.792 KJ

Explanation:

work done = KE = 1/2 mv^2

given;  m = 10g = 10/1000 kg =0.01 kg

           v = 400m/s

put the given  value in formula

KE = 1/2 X 0.01 X 400^2

KE = 1/2 X 0.01 X 400X 400

KE = 5/10 X 1/100 X 400 X400

KE = 5X 1 X 4 x40

KE = 800 J = initial KE

Final KE =  initial KE - 1% J

Final KE = 800 J - 1% J

Final KE = 800 - 800/100J

Final KE = 800 -8 J

Final KE = 792 J

Final KE = 0.792 KJ