Question

a body of mass 5 kg is thrown at an angle 45° to the horizontal on level ground with an initial velocity 10m/s.find the mean power(in watt) developed by gravity over the whole time of motion of the body​

Answer 1

Explanation:

The velocity of the body t sec. after the beginning of the motion becomes

V

ˉ

=

u

ˉ

+

gt

ˉ

The power developed by the gravity

mg

ˉ

at that moment is

P

ins

=

mg

ˉ

.

v

ˉ

=m(

g

ˉ

.

V

0

ˉ

+g

2

t)

=mg(gt−v

0

sinα)

As

mg

ˉ

is a constant force, so the e\average power,

p

av

=

T

A

=

T

mg

ˉ

.Δ

r

ˉ

where Δ

r

ˉ

is the net displacement of the body during time of the flight

as

mg

ˉ

⊥Δ

r

ˉ

so p

av

=0