The velocity of the car is given as, vc=30ms−1 And the velocity of ball with respect to the car is given as, vbc=20ms−1 Now we need to find the velocity of the ball with respect to the car with its components. vbc=20‌cos‌60∘‌i+20‌sin‌60∘‌j ⇒vbc=20×‌
1
2
i+20×‌
√3
2
j ∴vbc=10i+10√3j Now, we know that, vbc=vb−vc ⇒vb=vbc+vc ⇒vb=10i+10√3j+30i ∴vb=40i+10√3j Now we need to find the angle of projection. tan‌θ=‌
10√3
40
∴θ=tan−1(‌
√3
4
) Therefore, the required value of the angle of projection is tan−1(‌