Question

Two tall buildings are 30 m apart. The speed with which a ball must be thrown horizontally from a window 150 m above the ground in one building so that it enters a window 27.5 m from the ground in the other building is
a.2 m s^-1
b.6 m s^-1
c.4 m s^-1
d.8 m s^-1

Answer 1

Answer:

(b) 6 m s^-1

Explanation:

The distance between the building is taken as 30 meters, now the distance between the floor 150 m to window 27.5 m, is taken as

Distance, d = 150 - 27.5 = 122.5 m

Therefore, to find the time taken to cover this distance of 122.5 m is

S=u t+\frac{1}{2} a t^{2}S=ut+ 2/1 at 2

Now in the above equation, the value of initial velocity is taken as zero we get the time,

t =122.5=\frac{1}{2}(9.8) t^{2}122.5= 2/1 (9.8)t 2

The acceleration in the above formula is taken as a=9.8 m / s^{2}a=9.8m/s

2

Therefore, the time, t = 5sec

Now, the velocity to reach other building is

S = V x T, V = 30/5 = 6 m/sec