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1. A rubber stopper is whirled in a 1 1. A rubber stopper is whirled in a 1 m circle with a velocity of 8 m/s. If it m circle with a velocity of 8 m/s. If it generates 1.28 N of centripetal force generates 1.28 N of centripetal force what is the mass of the stopper?what is the mass of the stopper?

2. A brick sits on a plane with an 2. A brick sits on a plane with an incline of 20 degrees. If the mass of incline of 20 degrees. If the mass of the rock is 3 kg, what is the the rock is 3 kg, what is the magnitude of the component of the magnitude of the component of the weight force in the direction of the weight force in the direction of the plane?plane?

Questions on circular Questions on circular motion?motion?

Inclined Planes?Inclined Planes?

WorkWork

Work = Force x DistanceWork = Force x Distance– Units: Joules (J)Units: Joules (J)

Work can only be done by a force (or Work can only be done by a force (or component of force) in the same component of force) in the same direction as the motion.direction as the motion.

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

If a 10000 N force If a 10000 N force moves an 800 kg car 20 moves an 800 kg car 20

m, how much work is m, how much work is done? done?

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

Work at an angleWork at an angle. Take the . Take the component of force in the direction component of force in the direction of motion. of motion.

A sled is pulled 10 m by a rope which A sled is pulled 10 m by a rope which is at a 60 degree angle with the is at a 60 degree angle with the ground. If the force exerted on the ground. If the force exerted on the rope is 30 N how much work is done?rope is 30 N how much work is done?

A door is pushed open by a A door is pushed open by a 25 N force causing the handle 25 N force causing the handle

to make a circular arc. The to make a circular arc. The force is applied at a 90 force is applied at a 90

degree angle to the motion of degree angle to the motion of the door. If the handle moves the door. If the handle moves 1.7 m how much work is done 1.7 m how much work is done

on the door?on the door?

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

PowerPower

Power = work / timePower = work / time– Units: Watts (W)Units: Watts (W)

When lifting a 10 kg object 2 m. how When lifting a 10 kg object 2 m. how much work is done? If the lift takes 3 much work is done? If the lift takes 3 s, what amount of power is s, what amount of power is generated?generated?

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

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

HomeworkHomework

Pg 241 (1, 2, 4, 5, 18, 19, 21, 23, 27, Pg 241 (1, 2, 4, 5, 18, 19, 21, 23, 27, 29)29)

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