Na-
4. main bicycle traveling along a road.
5. explain can there be forces acting on an object if the object is at
rest? must there be an unbalanced force acting on a moving
object? explain your answers.
6. explain why does coating surfaces with oil reduce friction
between the surfaces?
7. distinguish between the mass of an object and the object's weight.
8. think critically suppose earth's mass increased but earth's diame-
ter did not change. how would the gravitational strength near
earth's surface change?

Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. which one, if either is correct? a. beryl, because low thermal conductivity results in low heat transfer. b. beryl, because low thermal conductivity results in high heat transfer. d. sapphire, because low thermal conductivity results in high heat transfer. e. neither, because low heat transfer is desirable both in summer and in winter.