Question

A particle is projected upwards from the roof of a tower 60 m high with velocity 20 m/s. find the
average speed upto its striking the ground​

Answer 1

Explanation:

u=20m/s

−60=20t−

2

1

gt

2

=20t−5t

2

(from second equation of motion)

⇒t

2

−4t−12=0⇒t=6,−2

t=6isthetimetillthestonereachesground.

distancecovered=60+2×

2g

u

2

=60+40=100

averagespeed=

6

100

=

3

50

m/s