Given:
Mass, m 50 g = 50 x 10^-3 kg
Final speed, v = 0
Initial speed, u = 250 ms^-1
Time, t = 1ms = 10^-3 s
To find: J = F x t = ? Average force, F = ma = ?
F=\(\frac { m(v-u) }{ t } \)
=\(\frac { 50\times { 10 }^{ -3 }[0-250] }{ 1\times { 10 }^{ -3 } } \)
F = 12500 = 1.25 x 10⁴ N
J = F x t
= 1.2 x 10⁴ x 10^-3
J = 12.50 Ns

Mass of first body, m₁ = 2 kg
Initial velocity of first body, u₁ = 40 ms^-1
Initial velocity of second body, u₂ = 0
Final velocity of first body,
v₁ z = Final velocity of the second body, v₂
i.e., v₁ = v₂= 20 ms^-1
To find : Mass of second body, m² = ?
According to law of conservation of momentum,
m₁u₁ + m₂u₂ = m₁v₁+ m₂v₂
m₁u₁ + m₂u₂ = v₁m₂ + m₂v₂
2 x 40 + m₂ x 0 =20 x 2 + 20 m₂
80 =40 + 20m₂
20 m₂ =40 ⇒ m₂
=\(\frac{40}{20}\) =2 kg
Mass of second body, m₂ = 2 kg

Impulse = Change in momentum
P = 60 N ; t = 10 s
Change in momentum = Force x time
= 60 x 10
Change in momentum = 600 Ns

Force, P = 200 dyne
Mass m = 10 g
t = 5 s
Acceleration, a=\(\frac { F }{ a } \Rightarrow a=\frac { 200 }{ 10 } \) =20 cm/s²
Velocity = at ⇒ v=20 x 5 =100 cm/s
In SI unit
v = 100 x 10^-2 ms^-1 (or) 1ms^-1
v = 1 ms^-1

Given:
Mass of the first body, m₁ = 20 kg
Mass of the second body, m₂ = 15 kg
Initial velocity of first body, u₁ = 40 ms^-1
Initial velocity of second body, u₂ = 0
(Second body is at rest initially)
Final velocity of the first body,
v₁ = Final velocity of the second body, v₂
i.e., v₁ = v₂ = v
According to law of conservation of momentum,
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
m₁u₁ + m₂u₂ =(m₁+m₂)v
20 x 10 + 15 x 0 = (20+15)v
800 = 35 v
Velocity, v=\(\frac{800}{35}\)
=22.85 ms^-1