Answer to Question #107220 in Mechanics | Relativity for james

Question

A block of mass m = 7.20 kg is released from rest from point circled A and slides on the frictionless track shown in the figure below. (Let ha = 8.00 m.)

Determine the block's speed at points circled B and circled C?


Determine the net work done by the gravitational force on the block as it moves from point circled A to point circled C?

Answer 1

This is a problem of energy conservation where

sum of initial kinetic and potential energy is equal to sum of final kinetic and potential energy

It is given that initially the block is at rest and it is at height 8 m

so initial kinetic energy = 0

initial potential energy = mgh =$7.2\times10\times8=576 J$

Since we are not provided with the exact location of B and C

so lets assume B is at height h_b and C is at height h_c so the spped can be calculated by this

$K_i+U_i=K_f+U _f$

$0+576=0.5\times m v^2 +mg(h_b\ or\ h_c)$