A knife thrower throws a knife toward a 300 g target that is sliding in her direction at a speed of 2.45 m/s on a horizontal frictionless surface. She throws a 22.5 g knife at the target with a speed of 36.0 m/s. The target is stopped by the impact and the knife passes through the target. Determine the speed of the knife (in m/s) after passing through the target.

Explanation:

We shall apply conservation of momentum  here because it is a case of inelastic collision

u₁ , u₂ initial velocity of knife and target . v₁ , v₂ be their final velocity.

m₁ u₁ + m₂u₂ = m₁v₁ + m₂v₂

u₂ will be negative as it is coming from opposite direction.

36 x 22.5 - 300 x 2.45 = 22.5 x v₁ + 0

810 - 735 = 22.5 x v₁

v₁ = 3.33 m /s

energy stored in the capacitor= 9.72 x 10⁻⁴ j

explanation:

the energy stored in the capacitor is given by

e= 1/2 c v²

e= energy stored

c= capacitance= 1.5 µc= 1.5 x 10⁻⁶f

v= potential difference=36 v

so energy stored= e= 1/2 (1.5 x 10⁻⁶) (36)²

energy stored= 9.72 x 10⁻⁴j