Question

Q6. A 120 g mass has a velocity = 21+5mis at a certain instant. Its kinetic energy is
1.
3 joule
2.
4 joule
3.
5 joule
4.
1.74 joule​

Answer 1

Explanation:

Here, m=120g=120×10

−3

kg=0.12 kg

v

=2

i

^

+5

j

^

ms

−1

∴v

2

=

v

.

v

=(2

i

^

+5

j

^

).(2

i

^

+5

j

^

)

=4+25=29 m

2

s

−2

Kinetic energy, K=

2

1

m.v

2

=

2

1

×0.12 kg×(29 m

2

s

−2

)=1.74 J.