ON A SEPARATE PIECE OF PAPER, answer the following questions in preparation for your Chapter 6 Summative Exam.

Learning Target #1: Explain the meaning of work.

  1. Define work.

Transfer of energy that occurs when a force makes an object MOVE

Learning Target #2: Describe how work and energy are related.

  1. What is the relationship between work and energy?

Energy is always being transferred from object doing work to object on which the work is being done

Both measured in Joules

Learning Target #3: Calculate the work done by a given force exerted on a body.

  1. What is the equation and SI unit for work?

Word = force x distance, SI Unit = Joules

  1. If you move a 50 N box to the parking lot 15 meters away, how much work will you do?

W = 50 x 15 = 750 J

Learning Target #4: Calculate power.

  1. What is the equation and SI unit for power?

P = Work/time, SI Unit = Watts

  1. How much power is used when a machine does 100 N of work in 5 seconds?

P = 100/5 = 20 Watts

Learning Target #5: Relate power to work, and solve problems involving acceleration, force, distance and time.

  1. Write out the equations for velocity, acceleration, force, work, and power.

V = distance/time, acc = v/time, F = ma, W = fd, P = w/t

  1. A school bus travels 200 meters in 4 seconds, determine the velocity.

V = 200/4 = 50 m/s

  1. If the school bus goes from 50 m/s to a complete stop, calculate the acceleration.

Acc = 50-0/4 = 50/4 = 12.5 m/s2

  1. How much force was applied by the breaks as the 10,000 N bus stopped in front of the school?

10,000 N

  1. How much work must the engine do for the bus to move 500 meters out of the parking lot?

W = fd = 10,000 N x 500 = 5,000,000 J

125,000 x 500 = 62, 500, 000 J

  1. How much power will the bus engine use in 2 hours?

P = w/t = 5,000,000 J/2 hr = 2,500,000 W

62, 500, 000 J/2 = 31, 250, 000 W

Learning Target #6: Explain how machines make work easier.

  1. A machine makes work easier by:

Increases applied force and/or changes direction of applied force

Same amount of work done with less effort (force) from you

Learning Target #7: Calculate the mechanical advantage of a machine.

  1. Define mechanical advantage.

Ratio of output force exerted by machine to input force

Number of times a machine multiples the input force

  1. What equation is used to calculate MA?

MA = output/input

  1. What is IMA?

Mechanical advantage of a machine without FRICTION

Learning Target #8: Calculate the efficiency of a machine.

  1. Define efficiency.

Measure of how much work put into the machine is transferred into output work by machine

  1. What equation is used to calculate efficiency?

Output work/input work x 100

  1. What role do lubricants play in efficiency of a machine?

Lubricants make machines more efficient by reducing friction

Learning Target #9: Describe and identify examples of the six types of simple machines.

  1. Define simple machine.

A machine that does work with one movement

  1. Define compound machine.

Combination of 2 or more simple machines

  1. What are the 2 families of simple machines?

Lever = lever, pulley, wheel & axle

Inclined plane = wedge, inclined plane, screw

  1. What is the difference between input (effort) force and output (load) force?

Input/effort = force YOU add to the machine

Output/load = force applied by the machine

Learning Target #10: Explain how the different types of simple machines make work easier.

  1. How does a 1st class lever make work easier?

By multiplying the force and changing the direction

  1. What is the IMA for a 1st class lever?

IMA = 1

  1. How does a 2nd class lever make work easier?

Always multiplies the force

  1. How do you determine the IMA for a 2nd class lever?

IMA = length of input arm divided by length of output arm

  1. How does a 3rd class lever make work easier?

Doesn’t multiply force but does increase distance over which force is applied

  1. How do you determine the IMA for a 3rd class lever?

IMA = length of input arm divided by length of output arm

  1. How does a fixed pulley make work easier?

Doesn’t multiple force, but changes direction

  1. What is the IMA for a fixed pulley?

IMA = 1

  1. How does a moveable pulley make work easier?

the wheel free to move, Multiples force

  1. What is the IMA for a moveable pulley?

IMA = 2

  1. What is the IMA for a block & tackle pulley determined?

Count the number of ropes supporting the weight

  1. A wheel & axle is a modified: ______

lever

  1. What is the IMA for a wheel & axle determined?

IMA = radius of wheel divided by radius of axle

  1. How does an inclined plan make work easier?

Increases distance which allows you to reduce the amount of force required to do work

  1. What is the IMA for a inclined plane determined?

IMA = length of slope (input distance) divided by height of slope (output distance)