Alarge raindrop-the type that lands with a definite splat-has a mass of 0.0014 g and hits your roof at a speed of 8.1 m/s. a. what is the magnitude of the impulse delivered to your roof? b. if the raindrop comes to rest in 0.37 ms, what is the magnitude of the force of the impact?

Answer

given,

mass of the drop, m = 0.0014 g

speed of the drop, u = 8.1 m/s

a) Change in momentum is equal to impulse

   final velocity of the drop, v = 0 m/s

   J = m ( v - u )

   J = 0.0014 x 10⁻³ x ( 0 - 8.1 )

   J = -1.134 x 10⁻⁵ kg.m/s

impulse of the roof = - J = 1.134 x 10⁻⁵ kg.m/s

b) time, t = 0.37 m s

   impact of force = ?

  we know

     J = F x t

   1.134 x 10⁻⁵ = F x 0.37 x 10⁻³

     F =  0.031 N

the magnitude of the force of the impact is equal to F =  0.031 N

a and b sometimes have a positive value