**Warm-UP your brain!** To help rearrange the furniture in your classroom, you exert a force of 20 N to push a desk 10 m. How much work do you do? If it takes you 5 seconds to move the desk, how much power do you produce? Place answers on a note card and place the note card in the fish bowl!

**To help rearrange the furniture in your classroom, you exert** a force of 20 N to push a desk 10 m. How much work do you do? Work = Force x distance W = 20 N x 10 m W = 200 Nm = 200 joules

**2. If it takes you 5 seconds to move the desk, how much** power do you produce? P = W = F x d t t P = 20 N x 10 m 5 s P = 200 joules 5 s P = 40 joules second = 40 watts

**Practice Sheet #15 Review** • A carpenter lifts a 400-N beam a distance of 1.2 meters. How much work is done on the beam? • Find ____________ Formula _____________________ • Given: Apply:

**Practice Sheet #15 Review** • A carpenter lifts a 400-N beam a distance of 1.2 meters. How much work is done on the beam? • Find _WORK___ Formula __W = F x d_____ • Given: Apply: F = 400N d = 1.2 m W = 400 N x 1.2 m W = 480 Nm = 480 joules Joules is abbreviated with J

**Practice Sheet #15 Review** • A dancer lifts a 200-N ballerina overhead a distance of 1.4 meters. How much work is done during the lift? • Find _WORK___ Formula __W = F x d_____ • Given: Apply: F = 200 N d = 1.4 m W = 200 N x 1.4 m W = 280 J

**Practice Sheet #15 Review** • Tom uses a 150-N force to try and move a bookcase from one wall in his library to another wall. Unfortunately Tom cannot move the bookcase. How much work does Tom do? • Find _WORK___ Formula __W = F x d_____ • Given: Apply: W = 150 N x 0 m W = 0 J NO Work was done! F = 150 N d = 0 m

**Practice Sheet #15 Review** • A motor exerts a force of 10,000 N to lift an elevator 6m in 5 seconds. What is the power produced by the motor? • Find _Power___ Formula __________________ • Given: Apply:

**Practice Sheet #15 Review** • A motor exerts a force of 10,000 N to lift an elevator 6m in 5 seconds. What is the power produced by the motor? • Find _Power___ Formula __P = (F x d) / t_____ • Given: Apply: P = (10,000 N x 6 m) 5 s P = 12,000 Nm s P = 12,000 watts or 12 kw F = 10,000 N d = 6 m t = 5 s

**Practice Sheet #15 Review** • A tow truck exerts a force of 9,000 N to pull a car out of a ditch. It moves the car a distance of 6 m in 25 seconds. What is the power of the tow truck? • Find _Power___ Formula __P = (F x d) / t_____ Given: Apply: P = 9,000 N x 6 m 25 s P = 2160 watts F = 9,000 N d = 6 m t = 25 s

**Practice Sheet #15 Review** • 6. Fill in the Blank: Complete each statement using a term from the list below. • Distance joules Work • Force W= F x d • Work needs two things: __________________ and ______________. • The formula for work is ____________________________________. • If there is no movement, there can be no ______________________. • Work is measured in ______________________________________.

**Practice Sheet #15 Review** • 6. Fill in the Blank: Complete each statement using a term from the list below. • Distance joules Work • Force W= F x d • Work needs two things: _Distance___ and __Force__. • The formula for work is ____________________________________. • If there is no movement, there can be no ______________________. • Work is measured in ______________________________________.

**Practice Sheet #15 Review** • 6. Fill in the Blank: Complete each statement using a term from the list below. • Distance joules Work • Force W= F x d • Work needs two things: _Distance___ and __Force__. • The formula for work is __W = F x d____. • If there is no movement, there can be no ______________________. • Work is measured in ______________________________________.

**Practice Sheet #15 Review** • 6. Fill in the Blank: Complete each statement using a term from the list below. • Distance joules Work • Force W= F x d • Work needs two things: _Distance___ and __Force__. • The formula for work is __W = F x d____. • If there is no movement, there can be no _work_____. • Work is measured in ______________________________________.

**Practice Sheet #15 Review** • 6. Fill in the Blank: Complete each statement using a term from the list below. • Distance joules Work • Force W= F x d • Work needs two things: _Distance___ and __Force__. • The formula for work is __W = F x d____. • If there is no movement, there can be no _work_____. • Work is measured in __joules__________.

**Practice Sheet #15 Review** • 7. Fill in the Blank: Complete each statement using a term from the list below. • Distance Force P = F x d • Time Watts t • Power needs three things: __________________ , ____________________ and ____________________. • The formula for power is ____________________________________. • Power is measured in ______________________________________.

**Practice Sheet #15 Review** • 7. Fill in the Blank: Complete each statement using a term from the list below. • Distance Force P = F x d • Time Watts t • Power needs three things: __Distance_ , ___Time__ and __Force____. • The formula for power is ____________________________________. • Power is measured in ______________________________________.

**Practice Sheet #15 Review** • 7. Fill in the Blank: Complete each statement using a term from the list below. • Distance Force P = F x d • Time Watts t • Power needs three things: __Distance_ , ___Time__ and __Force____. • P = F x d • The formula for power is ___________t___. • Power is measured in ______________________________________.

**Practice Sheet #15 Review** • 7. Fill in the Blank: Complete each statement using a term from the list below. • Distance Force P = F x d • Time Watts t • Power needs three things: __Distance_ , ___Time__ and __Force____. • P = F x d • The formula for power is ___________t___. • Power is measured in ___Watts_.

**Recall from yesterday, the scientific definition of work:** Work is the transfer of energy through a distance W=F x d

**A machine is a device that makes your task easier!** In general, machines allow you to overcome gravity, inertia, and/or friction in order to move something!

**A machine is any device that can change the strength of a** force, its speed, or its direction, but a machine does not reduce the amount of work to be done.

**Machines!** • Machines make work easier by changing: • The size of the force • The direction of the force • Both the size and direction of a force

**Machines!** Two types of forces are involved with machines: Resistance (Output Force) – the weight of the object to be moved Effort (Input Force) – the force that moves the resistance

**Mechanical Advantage** The number of times a machine multiples the effort force is the mechanical advantage (MA) of the machine. MA = resistance effort

**Example #5** Example #5: An inclined plane lets you move a 10-Newton weight (resistance) with an effort force of 5-Newtons. What is the mechanical advantage of the inclined plan? M.A.= resistance effort = 10 = 2 5 This means that the inclined plane doubles the effort

**Mechanical Advantage and Work** Different machines have different mechanical advantages. Remember no matter what the mechanical advantage is, the amount of work is the same!

**Simple Machine** A simple machine is a device that does work with only one movement.

**LEVERS**

**Definition of a Lever** A lever is a bar that is free to pivot, or turn, about a fixed point, the fulcrum.

**Pulleys** A pulley works something like a lever. Instead of a bar, a pulley has a rope.

**Wheel and Axle** A wheel and axle is a simple machine consisting of two wheels of different sizes that rotate together.

**Inclined Plane** A inclined plane makes it easier to lift something from a lower level to a higher level.

**Screw** A inclined plane wrapped around a center core.

**Wedge** Looks like two inclined planes placed back-to-back.

**Simple Machine** • 1. Lever • 2. Pulley • 3. Wheel and Axle • Inclined Plane • Screw • Wedge

**Today's Review** Please do not turn on your iResponse devices until instructed to do so.

**1. Simple machine does work with** iRespond Question Multiple Choice F A.) only one motion B.) electricity C.) at least two motions D.) E.)

**iRespond Question** Multiple Choice F 2. In general, machines allow you to ________________________ in order to move something! A.) overcome gravity B.) overcome friction C.) overcome inertia D.) all of the above E.)

**iRespond Question** Multiple Choice F 3. A machine is any device that can change the strength of a force, its speed, or its direction and a machine reduces the amount of work to be done. A.) True B.) False C.) D.) E.)

**iRespond Question** Multiple Choice F 4. The number of times a machine multiplies the effort force is the ____ of the machine. A.) Power B.) Force C.) Work D.) Mechanical advantage E.)

**5. If a lever has a mechanical advantage of 10, can a 500 N** rock be lifted with an effort force of 50 N? iRespond Question Multiple Choice F A.) Yes, it can be lifted B.) No, there is not enough force C.) Not enough information to determine the answer D.) E.)