Serving at a speed of 170 km/h, a tennis player hits the ball at a height of 2.5 m and an angle θ below the horizontal. The service line is 11.9 m from the net, which is 0.91 m high. What is the angle θ such that the ball just crosses the net? Will the ball land in the service box, whose out line is 6.40 m from the net?

6.11°

yes  

Explanation:

v = 170 km/h = 47.2 m/s

vx = v cos θ

vy = v sin θ

In horizontal direction, there is no acceleration.

vx t = 11.9

In vertical direction:

2.5 - 0.91 = vy t + 0.5 gt²

⇒1.59 = 11.9 tan θ + 4.9×0.25²× sec²θ            (∵g = 9.8 m/s²)

⇒1.59 = 11.9 tan θ + 4.9×0.25²× (1+tan²θ)

Solving for θ will give the result 6.11°

Displacement in x-direction

t = 0.375 s

vx t = 11.9

47.2 cos (6.11°) 0.375 s = 17.6 -11.9 = 5.7 m

The outline is 6.40 m from the net. Thus, the ball will fall in the service box.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach