A boy raises a 20.0 Kg rock 2.3 meters. What is the force that the boy uses to raise the rock?

Arod of some material 0.20 m long elongates 0.20 mm on heating from 21 to 120°c. determine the value of the linear coefficient of thermal expansion [in (degrees c)^-1] for this material.

You notice the birds sitting on the electrical wires which of the following explain why the birds don't get shocked

Identify the arrows that represent the process of cooling..