Question

Горизонтально летящая пуля массой 10г попала в лежащий на гладкой горизонтальной поверхности деревянный брусок массой 500г и застряла в нем. Какова была скорость пули, если брусок после выстрела приобрел скорость 10 м/с

Answer 1

Дано:

m1 = 10г (в данном случае массу можно не переводить в килограммы)

m2 = 500г 

V = 10 м/с

 

Найти: Vп

 

Решение:

По закону сохранения импульса:

m1 * Vп  + m1 * Vп = m1 * Vп` + m2 * Vб

 

Т.к. брусок до выстрела находила в покое, значит Vп = 0

И когда пуля попала в брусок, они стали иметь одинаковую массу и приобрели скорость 10 м/с

 

m1 * Vп + 0 = V(m1 + m2)

m1 * Vп = V(m1 + m2)

Vп =  $\frac{V(m1 +m2)}{m1}$

Vп = $\frac{10 (500+10)}{10} = \frac{10 * 510}{10} = \frac{5100}{10}$  = 510 м/с

 

 

Answer 2

Calculation of Bullet Velocity

To determine the velocity of the bullet, we can use the principle of conservation of momentum. The momentum before the bullet hits the wooden block is equal to the momentum after the bullet becomes embedded in the block.

The momentum of an object is calculated by multiplying its mass by its velocity. In this case, the momentum of the bullet before impact is given by:

Momentum of bullet before impact = mass of bullet × velocity of bullet

The momentum of the wooden block after the bullet becomes embedded in it is given by:

Momentum of block after impact = (mass of bullet + mass of block) × velocity of block

Since the momentum is conserved, we can equate the two expressions:

mass of bullet × velocity of bullet = (mass of bullet + mass of block) × velocity of block

Given that the mass of the bullet is 10 g (0.01 kg), the mass of the block is 500 g (0.5 kg), and the velocity of the block after the impact is 10 m/s, we can solve for the velocity of the bullet.

Let's calculate it:

0.01 kg × velocity of bullet = (0.01 kg + 0.5 kg) × 10 m/s

Simplifying the equation:

0.01 kg × velocity of bullet = 0.51 kg × 10 m/s

velocity of bullet = (0.51 kg × 10 m/s) / 0.01 kg

velocity of bullet = 51 m/s

Therefore, the velocity of the bullet was 51 m/s when it hit the wooden block