Chapter 8.7, Problem 12WE

To determine

the force due gravitational pull and check whether we can keep the car from rolling down the hill by pushing it against the gravitational pull.

Answer to Problem 12WE

a. Force of gravity is 157 pounds.

b. 157 pounds of force is very high. Hence, we cannot push the car against this force.

Explanation of Solution

Given:

Force of gravity pulling a 3000 lb car on a hill with angle of elevation $3°$ .

Calculation:

a.

  $\begin{array}{l}\text{Force = 3000}\times \sin 3°\text{,}\\ \Rightarrow \text{Force = 3000}\times \text{0}\text{.052}\\ \Rightarrow \text{ Force = 157}\text{pounds}\text{.}\end{array}$

b. 157 pounds of force is very high. Hence, we cannot push the car against it.