A particle of mass 100 g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time the particle goes up is :

Question

A particle of mass 100 g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time the particle goes up is : (A) -0.5 J (B) -1.25 J (C) 1.25 J (D) 0.5 J

Tardigrade Admin · Accepted Answer

The height (h)traversed by particle while going up is

h = \frac{u ^{2}}{2 g} = \frac{25}{2 \times 9.8}

Work done by gravity force =

m g . h

= 0.1 \times g \times \frac{25}{2 \times 9.8} cos 18 0^{\circ}

[Angle between force and displacement is 180°]

∴ W = 0.1 \times \frac{25}{2} = 1.25 J

Q. A particle of mass 100 g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time the particle goes up is :

-0.5 J

-1.25 J

1.25 J

0.5 J

The height (h)traversed by particle while going up is h=2gu2​=2×9.825​ Work done by gravity force =mg​.h =0.1×g×2×9.825​cos180∘ [Angle between force and displacement is 180°] ∴W=0.1×225​=1.25J

The height (h)traversed by particle while going up is
$h = \frac{u ^{2}}{2 g} = \frac{25}{2 \times 9.8}$
Work done by gravity force = $m g . h$
$= 0.1 \times g \times \frac{25}{2 \times 9.8} cos 18 0^{\circ}$
[Angle between force and displacement is 180°]
$∴ W = 0.1 \times \frac{25}{2} = 1.25 J$