Question

A particle is thrown at time t = 0 with a velocity of `10 ms^(-1)` at an angle `60^@` with the horizontal from a point on an inclined plane, making an angle of `30^@` with the horizontal. The time when the velocity of the projectile becomes parallel to the incline is

A. `2/(sqrt3) s`
B. `1/(sqrt3) s`
C. `sqrt3 s`
D. `1/(2(sqrt3)) s`

Answer 1

Correct Answer - B
b. `v_y = v sin 30^@ - g cos 30^@t`

`t= (vsin30^@)/(gcos30^@) = v/g 1/(sqrt3) = 1/(sqrt3)s`.