# Science ch2 lesson 3

1. _________ states that an object’s acceleration is the ratio of net force to the object’s mass.

Newton’s second law of motion.

2. Define centripetal force in your own words.

Centripetal force is the force that acts perpendicular to the velocity of a object and towards the center of a circle.

3. Explain how you know the forces acting on an object at rest are balanced.

Because for a object to be at rest there must be no net force moving it, and for there to be no net force you need either no forces on a object or for all forces to counteract each other.

4. Compare how your weight, mass, and the normal force exerted by the floor change when you are in an elevator that starts from rest and accelerates upward.

when you are on a elevator that begins to accelerate from a stop upwards Your weight, as it is a measurement of the force exerted by gravity on a object, stays the same, your mass also stays the same, but the normal force increases.

5. How does the velocity of an object traveling in a straight line change if a nonzero net force acts in the same direction as the object’s velocity?

The velocity increases.

6. Calculate – The net force on a rock with a mass of 2.0 kg is 19.6 N. What is the acceleration of the rock?

9.8m/s^2

7. Calculate – At the start of a race, the net force on a sprinter is 640 N. If the mass of the sprinter is 80.0 kg, find the sprinter’s acceleration.

8m/s^2

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