Question

A girl swings on a playground swing in such a way that at her highest point she is 3.9 m from the ground, while at her lowest point she is 0.9 m from the ground. 9.9 m 3.9 m 0.9 m What is her maximum speed? The acceleration due to gravity is 9.8 m/s 2 .

Answer 1

Step-by-step explanation:

Given

height of girl at top point is
`h_1=3.9\ m`

height at bottom point is
`h_2=0.9\ m`

Suppose girl possess maximum velocity at bottom point so her kinetic energy is converted to Potential energy

kinetic energy
`K=(1)/(2)mv^2`

Gain in Potential Energy
`\Delta U=mg(h_1-h_2)`

`K=\Delta U`

`(1)/(2)mv^2=mg(h_1-h_2)`

`v=√(2g(h_1-h_2))`

`v=√(2* 9.8* (3.9-0.9))`

`v=√(58.8)`

`v=7.66\ m/s`