Question

A ball is moving with speed 20 m/s collids with a smooth Surface as show in figure. The magnitude of change in velocity of th ball will be​

Answer 1

Answer:

20√3

Explanation:

Since velocity is a vector, we can divide it into x and y components.

Here, the velocity component along x axis is not changin (it is constant). Thus the difference is 0

Considering for the y component, we have to subtract the final from intial, But since the vertical component of initial velocity is opposite to that of final velocity, we have to add both magnitude. ie vcos30+vcos30=20*2*√3/2=20√3

Answer 2

Given :-

Velocity of ball = v = 20 ms-¹

Angle of Projection = Ø = 60°

Initial Velocity of ball,

u = - v Sin60° î + v Cos60° j

Final Velocity,

v = v Sin60° î + v cos60° j

∆V = v - u

∆V = v Sin60° î + v cos60°j -(-v Sin60°î + v Cos60°j)

∆V = v Sin60° î + v Cos60° j + v Sin60°î - v Cos60°j

∆V = 2v Sin60° î

∆V = 2 × 20 × √3/2

∆V = 20√3 ms-¹