Simple Machines Objectives: Levers Torque and Levers Gears, Pulleys, and the Wheel-and-Axle

Gears: Transfer of Rotational Motion T . N = t . n T: Number of teeth on the driver gear t: Number of teeth on the driven gear N: Number of revolutions on the driver gear n: Number of revolutions on the driven gear Q5. A motor turning at 1250 rpm is fitted with a gear having 54 teeth. Find the speed of the driven gear if it has 45 teeth.

Torque Review Torque = (Force ) x (Lever Arm) Q6. Which wrench requires you to apply less force in order to loosen a bolt. A long wrench or a short wrench? (a) The long wrench (b) The short wrench (c) It doesn’t matter

Levers (Effort Force)(Effort Arm) = (Resistance Force) (Resistance Arm) Q7. (A first-class lever) A 10-lb objects is placed 1 ft to the left of fulcrum. How far from the fulcrum should a 5-lb force be applied to balance it.

Levers (Effort Force)(Effort Arm) = (Resistance Force) (Resistance Arm) Q8. (A first-class lever) A 10-lb objects is placed 1 ft to the left of fulcrum. How far from the fulcrum should a 5-lb force be applied to balance it.

Gears and Simple Machines 20 P4. A wheel barrow 6.00 ft long is used to haul a 180-lb load. How far from the wheel is the load placed so that a person can lift it with a force of 45.0 lb? 6.0 ft ??? ft 180 lb Pivot (Fulcrum) Ans.

Gears and Simple Machines 20 P5. A bar is used to raise a 1200-N stone. The pivot is placed 30.0 cm from the stone. The worker pushes 2.50 m from the pivot. What is the mechanical advantage? What force is exerted? Ans.

Mechanical Advantage (Effort Force)(Effort Arm) = (Resistance Force) (Resistance Arm) = Effort Arm Resistance Arm Resistance Force Effort Force Resistance Force Mechanical Advantage = Effort Force

The Wheel-and-Axle Q9. A wheel with radius 75.0 cm is attached to an axle of radius 13.6 cm. What force must be applied to the rim of the wheel to raise a 1000-N weight? = Effort Arm Resistance Arm Resistance Force Effort Force

Gears and Simple Machines 20 P1. A driver gear with 60 teeth makes 1600 rpm. How many teeth must the driven gear have if it makes 480 rpm? Ans. P2. The larger of two gears in a clock has 36 teeth and turns at a rate of 0.50 rpm. How many teeth does the smaller gear have if it rotates at 1/30 rev/s? Ans. P3. An axle of radius 12.0 cm is used with a wheel of radius 62.0 cm. What force must be applied to the rim of the wheel to lift a weight of 975 N? Ans.