1. Warm Up 1. A rubber stopper is whirled in a 1 m circle with a velocity of 8 m/s. If it generates 1.28 N of centripetal force what is the mass of the stopper? 1. A rubber stopper is whirled in a 1 m circle with a velocity of 8 m/s. If it generates 1.28 N of centripetal force what is the mass of the stopper? 2. A brick sits on a plane with an incline of 20 degrees. If the mass of the rock is 3 kg, what is the magnitude of the component of the weight force in the direction of the plane? 2. A brick sits on a plane with an incline of 20 degrees. If the mass of the rock is 3 kg, what is the magnitude of the component of the weight force in the direction of the plane?

2. Questions on circular motion? Inclined Planes?

3. Work Work = Force x Distance Work = Force x Distance –Units: Joules (J)‏ Work can only be done by a force (or component of force) in the same direction as the motion. Work can only be done by a force (or component of force) in the same direction as the motion.

4. If a 10 N force moves an air hockey paddle 0.5 m how much work is done?

5. If a 10000 N force moves an 800 kg car 20 m, how much work is done?

6. . If a 50 N force is applied to a wall for 7 s, how much work is done?

7. Work at an angle. Take the component of force in the direction of motion. Work at an angle. Take the component of force in the direction of motion. A sled is pulled 10 m by a rope which is at a 60 degree angle with the ground. If the force exerted on the rope is 30 N how much work is done? A sled is pulled 10 m by a rope which is at a 60 degree angle with the ground. If the force exerted on the rope is 30 N how much work is done?

8. A door is pushed open by a 25 N force causing the handle to make a circular arc. The force is applied at a 90 degree angle to the motion of the door. If the handle moves 1.7 m how much work is done on the door?

9. A wheelbarrow is pushed 15 m along the ground by a 7 N force applied at a 45 degree angle. How much work is done on the wheelbarrow? A wheelbarrow is pushed 15 m along the ground by a 7 N force applied at a 45 degree angle. How much work is done on the wheelbarrow?

10. Power Power = work / time Power = work / time –Units: Watts (W)‏ When lifting a 10 kg object 2 m. how much work is done? If the lift takes 3 s, what amount of power is generated? When lifting a 10 kg object 2 m. how much work is done? If the lift takes 3 s, what amount of power is generated?

11. A donkey pulls a cart 80 m, with a force of 400 N in 15 s, how much power is generated? A donkey pulls a cart 80 m, with a force of 400 N in 15 s, how much power is generated?

12. Two sled dogs each exert 50 N of force in front of the sled, each dog’s rope makes a 15 degree angle with the line directly in front of the sled. If the sled is pulled 6000 m in 1 hour, how much work is done by each dog on the sled? How much total work is done on the sled? How much power is generated by each dog? How much power is generated total? Two sled dogs each exert 50 N of force in front of the sled, each dog’s rope makes a 15 degree angle with the line directly in front of the sled. If the sled is pulled 6000 m in 1 hour, how much work is done by each dog on the sled? How much total work is done on the sled? How much power is generated by each dog? How much power is generated total?

13. Homework Pg 241 (1, 2, 4, 5, 18, 19, 21, 23, 27, 29)‏ Pg 241 (1, 2, 4, 5, 18, 19, 21, 23, 27, 29)‏ Test Review Worksheet Test Review Worksheet