Chapter+15+-+Motion

Chapter 15-Objects in Motion
 * What causes motion and how does it affect us?

Vocabulary
1. relative motion-Change in position of one object compared to the position of some fixed object.

2. frame of reference- Objects that don't seem to move define your frame of reference.

3. speed- The rate at which an object's position changes.

4. velocity- The speed and the directionan object is moving.

5. force- Any push or pull.

6. friction- Force that acts when two surfaces rub together.

7. work- Using force in order to move an object a certain distance.

8. kinetic energy- Energy of motion.

9. potential energy- The amount of energy available to do work because of the way a system is arranged.

10. gravity- An attractive force between two or more objects over a distance. the more mass an object has, the stronger the gravitational force.

What can change a marble's speed?

(1) Roll a marble down a ramp. Time how long it takes to move 180 cm. Find the speed.

(2) __Predict__ how raising the ramp would change the speed.

Explain your results. (1)Interpret Data: make a bar graph to show your results.

(2)How did raising the heightof the ramp change the speed of the marble?

what are 3 types of motion? (1)back and forth(2)curve (3)straight

__relitave motion__ You compare objects that change position with objects that don't. The change in one object's position compared to the other is __relative motion.__

Capter 15 reviewpg.454-455 1.potential energy 2 force 3.velocity 4.work 5.relative motion 6.gravity 7.frame of reference 8.kinetic energy 9.Gravity is the force that causes the ball to roll down the ramp. You need a force to overcome the force of gravity to push the ball up the ramp. 10.Friction between the ball and the grass will ruduce the speedof the ball and finally make it stop. 11.A full grocery cart has more mass than an empty grocery cart.An object with more mass takes more force to move that is why the full cart is harder to push. 12.Without friction between your shoes and the sidewalk, it would be impossible or almost impossible to walk. Your shoes wouldn't grip the sidewalk and you would probably slip and fall. skip 13. 14.First, I bought a ticket. Next, I stood in line and waited my turn. Then I got on the roller coaster and fastened my seat belt. Finally, the ride started and I had fun. 15.-B- 16.-H- 17.-A- 18.-H- skip 19.