Chapter 2:
Q2.2
Weight is the force of gravity on an object. Something is weightless if it is far from other objects such as the earth or the sun. We will later see that some objects in free fall or orbit appear weightless.
Q2.3
Friction with the roof and wind (air drag).
Q2.7
Southeast, the same direction as the vector sum of the forces.
Q2.8
While subject to a centripetal force, it moves in a circle. If the force suddenly disappears, it moves in a straight line in the same direction it was going when the force was removed.
P2.2
P2.3
P2.5
P2.7
C2.1.
When you swing the bat, you exert moderate force over several tenths of a second, giving it a substantial speed. When it encoutners the baseball, both are very hard, which means they bounce off each other in a very short time, perhaps thousandths of a second. For the bat to change the baseball so much in so little time, the force must be huge.
We can talk more about this after we discuss momentum and energy.