Answer to Question #87017 in Classical Mechanics for Bhargavi M

Question

A projectile is projected with a speed 30 m/s at an angle 30° with the vertical. The speed of the projectile when its direction of motion makes an angle 30° with the horizontal is ? Options 1 ) 10 m/s
2) 20 m/s , 3) 10*3^2 4) 20*3^2

Answer 1

Initially, vertical speed was:

$$v_{hor0}=30*\sin30^\circ=15m/s$$

Horizontal speed is constant(as no forces act in horizontal direction)

When, the speed made 30° with horizontal, total speed is:

$$v=\frac{v_{hor}}{\cos30^\circ}=17.3 m/s$$

Answer: 17.3 m/s