# Review Sheets Unit 3 4.

3.

2.

1.

Define static friction and kinetic friction.

Name: ______________________

SPH 4C – Review Test 3

Mechanical Systems

Fill in your answers in the spaces provided below. This completed packet is due at the beginning of tomorrow’s class,

BEFORE THE TEST.

What is a coefficient of friction?

The normal force between a snowmobile and the snow has a magnitude of 2200 N; the horizontal force need to the get the snowmobile to just start moving has a magnitude of 140 N. Calculate the appropriate coefficient of friction.

In a ramp experiment, a brick slides at a constant velocity down a wooden board. A student finds that the height of one end of the board above the other end is 0.80 m, and the horizontal “run” of the inclined plane is 2.3 m. Determine the coefficient of kinetic friction between the surfaces.

5.

A 73 kg hockey player glides across the ice with steel blades. Calculate the magnitude of the force of kinetic friction acting on the skater. (Refer to the table on page 53 of your textbook.)

6.

Name three situations when you think it would be important to have extra friction.

7.

Name three situations when you think it would be important to reduce friction.

8.

Name all of the members of the lever family of simple machines.

9.

Name all of the members of the inclined plane family of simple machines.

10.

Determine the class of each of the following levers.

11.

List all of the simple machines that can be found as part of the following compound machines.

12.

A first-class lever, 2.8 m long, has a load force of magnitude

6.8 × 10

2

N located 1.2 m from the fulcrum.

Calculate the magnitude of the effort force at the end of the lever needed to balance the load.

13.

A wheelbarrow has a 95 kg load located 0.60 m from the fulcrum. An effort force of magnitude

5.2 × 10

2

N is needed to lift the handles of the wheelbarrow. a) Calculate the magnitude of the load force. b) Calculate the distance from the effort force to the load.

14.

A camper is using a large plank as a first-class lever to move a rock. The effort force has a magnitude of

450 N, and the distance from the fulcrum to the effort force is 2.2 m. What is the magnitude of the effort torque produced?

15.

What is torque?

16.

An emergency crew is using a plank as a first-class lever to raise one side of a car off the road. The fulcrum is a large block of wood. The magnitude of the load force is 5200 N and that of the effort force is 650 N; the load arm and effort arm are 0.40 m and 3.6 m, respectively. Calculate the a) AMA b) IMA c) Percent efficiency of the plank.

17.

Match each of the following equations for IMA with the correct simple machine. 𝑑

𝐸 𝑑

𝐿

Number of upward strands. 𝑙𝑒𝑛𝑔𝑡ℎ ℎ𝑒𝑖𝑔ℎ𝑡 𝑟

𝐸 𝑟

𝐿

𝑁

𝐸

𝑁

𝐿 set of pulleys inclined plane lever set of gears wheel and axle

18.

Is the IMA greater than or less than the AMA? Why?

19.

Define each of the following and give two examples of each.

Term

Biomechanical

System

Domestic Machine

Industrial Machine

Block and Tackle

Chain Hoist

Compound Machine

20.

What is work?

Definition

21.

What conditions need to be met for work to be done?

Examples

22.

A toboggan carrying two children (total mass 85 kg) reaches its maximum speed at the bottom of a hill. It then glides to a stop in 21 m along a horizontal surface. The coefficient of kinetic friction between the toboggan and the snowy surface is 0.11. Calculate the work done by the force of friction on the toboggan.