1. We get a stiffer spring by using a:

Group of answer choices

a.lower Young's Modulus.

b.bigger cross section area.

c.longer length.

d.thinner spring.

2.Compare two tires, one filled with hollow air and one solid rubber, the two have the same:

Group of answer choices

a.friction.

b.density.

c.price.

d.weight.

3. A car has more control when the tires are:

Group of answer choices

a.leaking.

b.skidding.

c.not rolling.

d.rolling.

4. Tires are made of rubber and NOT iron to increase:

Group of answer choices

a.not rolling.

b.friction.

c.leaking.

d.rolling.