Question

2. A bullet moving with speed 100m/s, gets embedded in the trunk of a tree. It comes to
rest after 5 cm. Find the deceleration offered by the tree. Find the force felt by the bullet if its mass is 100g.
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Answer 1

Correct Question

A bullet moving with speed 100m/s, gets embedded in the trunk of a tree. It comes to rest after 5 sec. Find the deceleration offered by the tree. Find the force felt by the bullet if its mass is 100g.

Solution-

A bullet moving with a speed of 100 m/s (here the initial velocity of the bullet is 100 m/s). The bullet embedded in the trunk of a tree and comes to rest after 5 sec. (Final velocity of the bullet is 0 m/s and time is 5 sec).

We have to find the deceleration offered by the tree.

Using the First Equation Of Motion:

v = u + at

Substitute the known values,

→ 0 = 100 + a(5)

→ -100 = 5a

→ -20 = a

(Negative sign shows retardation)

Therefore, the deceleration offered by the tree is 20 m/s².

Also given that, mass of the bullet is 100 g.

We have to find the force felt by the bullet.

1 g = 0.001 kg

100 g = 0.1 kg

Force is defined as the product of mass and acceleration.

F = ma

Substitute the values,

→ F = 0.1 × (20)

→ F = 2

Therefore, the force felt by the bullet is 2N.

Answer 2

Answer:

Explanation:

Correct Question,

A bullet moving with speed 100m/s, gets embedded in the trunk of a tree. It comes to rest after 5 sec. Find the deceleration offered by the tree. Find the force felt by the bullet if its mass is 100g.

Solution,

Here, we have

Initial velocity, u = 100 m/s

Final velocity, v = 0

Time taken, t = 5 sec

Mass, m = 100 g = 100/1000 = 0.1 kg

To Find,

Deceleration, a = ?

Force, F = ?

Now, According to the 1st equation of motion,

We know that

v = u + at

So, putting all the values, we get

v = u + at

⇒ 0 = 100 + a × 5

⇒ - 100 = 5a

⇒ - 100/5 = a

⇒ a = - 20 m/s²

Hence, the deceleration of the bullet is - 20 m/s².

Now, we will find out Force,

We know that,

F = ma

So, putting all the values, we get

F = ma

⇒ F = 0.1 × 20

⇒ F = 2 Newtons.

Hence, the force felt by the bullet if its mass is 100 g is 2 Newtons.