Question

A ball is thrown vertically up from top of a tower
of height 35 m with speed of 30 m/s. By what
speed it will hit the ground?
​

Answer 1

Answer:10√7

Explanation:

as we know speed before hitting the ground (v)=√2gh. So by using the given value we can calculate this

height (given)=35m

g=10

so use formula

v=√2×10×35=10√7                                                              

Answer 2

Answer:40 m/s

Explanation:

Ball is thrown upwards,So

v=0

u=30m/s

v²=u²-2gh

0=30×30-2×10×h

h=900÷20

h=45m(Distance travelled by ball upwards)

Total distance travelled before hitting ground:35+45=80m

So

u=0

h= -80m

Speed by which it hits the ground-

v²=u²-2gh

v²=0-2×10×-80

v=√1600

v=40m/s