1. The three pieces of information necessary to determine the amount of gravity between the earth and the moon are:
- The mass of the earth
- The mass of the moon
- The distance between the centers of the earth and the moon
2.
a. If one mass is doubled, the force of gravity between the masses doubles.
b. If both masses are doubled, the force of gravity between the masses quadruples.
c. If one mass is tripled, the force of gravity between the masses triples.
d. If the distance between them is cut in half, the force of gravity between the masses increases by a factor of four.
3. If an object is falling through the air and its speed is constant, it is traveling at terminal velocity. At this speed, the force on the object is balanced (net force is zero). The object is no longer accelerating. It falls at a constant speed.
4. A leaf will reach terminal velocity faster than a loaf or an acorn falling from the top of a tall oak tree. This is because the leaf has a larger surface area relative to its mass, which increases air resistance and causes it to reach terminal velocity more quickly.
5. When you are in free fall, you are accelerating at approximately 9.8 m/s² downward due to gravity. You feel weightless because there is no normal force acting on you — you and your surroundings are accelerating together.
6. The net force on the player is 100 N to the east. Since the forces are in opposite directions, subtract the smaller force from the larger: 120 N east – 20 N west = 100 N east. The player will accelerate to the east.
Parent Tip: Review the logic above to help your child master the concept of friction and gravity worksheets.
