Question

2. A body of mass 2 kg is projected at an angle of 60°
to the horizontal with a speed of 20 m/s. The work
done by gravity by the time the velocity vector
makes 30° to the horizontal (g = 10 m/s2)



(a)800/3 J

(b)-800/3 J

(c) 400/3 J

(d) -400/3 J​

Answer 1

Answer:

Velocity of the highest point,

V

x

=Vcosθ=20×cos60

∘

=20×

2

1

=10m/s

Now the angle between the horizontal velocity and the gravitational force θ=90

∘

Power=fvcosθ=mgvcos90

∘

=0 (Since cos90

∘

=0)