A particle of mass 20 g is thrown vertically upwards with a speed of 10 m/s. Find the work done by the force of gravity during the time the particle goes up.

Explanation

Suppose the particle reaches a maximum height h. As the velocity at the highest point is zero, we have
`0=u^2-2gh`
`or, h=u^2/(2g)`
the work done by the force of gravity is `
`-mgh=-mg u^2/(2g=-1/2 mu^2`
`=-1/2(0.02kg)xx(10 m/s)^2=-1.0J`.