Question

bullet of mass 50g is moving with a velocity of 500 m/s. It penetrates 10cm into a

still target and comes to rest. Calculate

a. the kinetic energy possessed by the bullet

b. the average retarding force offered by the target​

Answer 1

Answer:

a.25 b.62500

Explanation:

a.)m×a=f

kinetic energy is = 50/1000(convert to kg)

=0.05 kg × 500=25

Answer 2

Given:-

→ Mass of the bullet = 50g

→ Initial velocity of the bullet = 500m/s

→ Distance the bullet penetrates = 10cm

To find:-

→ Kinetic energy possessed by the bullet.

→ Average retarding force offered

by the target.

Solution:-

Firstly, let's convert the mass of the bullet from g to kg.

=> 1g = 0.001kg

=> 50g = 50(0.001)

=> 0.05g

=> K.E. = 1/2mv²

=> K.E. = 1/2×0.05×500×500

=> K.E. = 25×250

=> K.E. = 6250 J

Let's convert the given distance from

cm to m.

=> 1cm = 0.01m

=> 10cm = 10(0.01)

=> 0.1m

Now, we have to calculate the acceleration of the bullet using the 3rd equation of motion:-

=> v² - u² = 2as

=> 0 - (500)² = 2×a×0.1

=> -250000 = 0.2a

=> a = -250000/0.2

=> a = -1250000 m/s²

Hence, let's calculate the required retarding force by using the 2nd Law of motion :-

=> F = ma

=> F = 0.05(-1250000)

=> F = -62500 N

[Here,-ve sign represents retarding force]

Thus :-

• Kinetic energy possessed by the bullet

is 6250 J .

• Average retarding force offered by the

target is 62500 N .