Question

Joshua was driving to a friend’s house to study. During his trip, he started on pavement. At one point, he hit an ice patch on the road, but then he returned to pavement. The road then turned into a gravel road. Which best describes the frictional force of his trip?
a. Friction increased when he went from pavement to ice and then decreased two more times.
b. Friction decreased when he went from pavement to ice and then increased two more times.
c. Friction increased when he went from pavement to ice and then decreased one additional time.
d. Friction decreased when he went from pavement to ice and then increased one additional time.

Answer 1

Answer:

b. Friction decreased when he went from pavement to ice and then increased two more times.

Explanation:

Frictional force depends on the normal force of the surface and a friction coefficient.

$F_{f} = -\mu N$

Since we're talking about the same car, the value of $N$ will remain constant whereas μ will represent the change in the frictional coefficient of the surface. Now we consider the different surfaces, cars will slide in an icy road which means that the frictional coefficient is smaller than the pavement.

After Joshua returns to the pavement road, the resulting frictional force increases and will do so one more time when he reaches the gravel road. Gravel roads have greater frictional coefficients than pavement roads which means the frictional force will increase a second time.

Answer 2

Answer:

b

Explanation: