4.4 and 4.5Applications to automobiles, sports and research

p. 179-188 read and make notes on :Car tires, car breaks, electronic stability controls, crash

testing, airbags, golf club design, footwear design,

Section 4.4

Forces Applied to Automotive Technology

One seat belt design pulls the passenger into an optimal crash position after a computer detects a crash or a strong, sudden stop. The animation shows the piston going up and turning the rack gear, which pulls in the seat belt.

Why were earlier seat belt designs harmful to passengers? Discuss how the design shown here is less harmful.

Discussion: Forces Applied to Automotive Technology

Section 4.4

Answers for Discussion Questions:

Sample answer: Earlier seat belt designs hurt passengers because the seat belt applied huge forces on the passenger during the crash or stop. The design shown in the animation, called a pretensioner, reduces the applied force by reeling in the seat belt, which puts the passenger in a less dangerous position for the crash.

Section 4.4

Using the terms below, label each circled area of the images.

Forces Applied to Sports and Research Section 4.5

increase force of static friction

decrease force of kinetic friction

increase coefficient of static friction

For each sport illustrated here, discuss the advantage or purpose of adjusting the force or friction coefficient.

Discussion: Forces Applied to Sports and Research Section 4.5

Using the terms below, label each circled area of the images.

Forces Applied to Sports and Research Section 4.5

increase force of static friction

decrease force of kinetic friction

increase coefficient of static friction

Answers for Discussion Questions:

Sample answer: The golf grip is made of rubber or leather. These materials increase the force of static friction between the club and the golfer’s hands. By increasing the force of static friction, it is more difficult for the hands to slip, thus allowing the golfer more control. When skating, it is preferable to reduce the force of kinetic friction so that the skater can move faster and more easily. When running, the runner does not want to slip and possibly cause injury, so the soles are designed to increase the coefficient of static friction.

Section 4.4

Compare all-season tires and snow tires by completing the table using the terms below.

All-Season Tires versus Snow Tires Section 4.6

All-Season Tires Snow Tires

How are they similar?

How are they different?

• temperature

• weather conditions

• logo

• snow crystal• all conditions• colder

temperatures

• prevent hydroplaning

• no logo• snow and ice

• provide traction• all temperatures

Compare all-season tires and snow tires by completing the table using the terms below.

All-Season Tires versus Snow Tires Section 4.6

All-Season Tires Snow Tires

How are they similar?

• prevent hydroplaning

• provide traction

How are they different?

• all temperatures • temperature • snow and ice

• all conditions • weather conditions

• colder temperatures

• no logo • logo • snow crystal