Physics

1. Metric System – Unit of Mass is the kilogram and the unit of weight is newton’s.

English System – Unit of Mass is the pound and the unit of weight is slug.

2. In the absence of acceleration mass and weight are directly proportional to each other. If the mass of an object is doubled, its weight is doubled. An object has the same mass on earth as it does on the moon. The weights however are different due to the force of gravity that is acting on the mass.

3. The acceleration of an object is directly proportional to the net force acting on the object but is inversely proportional to the mass. If a brick is pushed the acceleration of the brick would be faster than that of two bricks stacked on top of each other. This is due to the mass of the two bricks weighing more than just 1 by itself.

4. A. In air, the greater the mass of an object the greater the rate of acceleration in free fall.

B. The Mass of an object does not affect the acceleration in a vacuum because air resistance is neglected; therefore the net force becomes the weight.

5. 1/3rd

6. Vectors have direction whereas scalar quantities do not. A vector would be an arrow pointing in a direction, or a car moving in a given direction, whereas a scalar quantity would be the car at a stand still or a car at a given speed, but not going anywhere, say on a giant treadmill.

7. When running on the road, your feet push on the road, and the road pushes on your feet. This demonstrates equal and opposite reaction.

8. A. Hammer hitting the nail is the action, and the reaction is the nail being driven down.

B. The earth’s gravity pulling on the book is the action, and the reaction would be the book falling.

C. A helicopter blade pushing the air downward is the action, and the air pushing the helicopter blade upward is the reaction.

9. A. 30 newton’s

B. .5 m/s (squared)