When a 430-g soccer ball is kicked, the impact lasts for 0.04 s. In order for the ball to fly off at 8 m/s, the force of the kick must be
A) 86 N.
B) 138 N.
C) 178 N.
D) 86 kN.

Question

Quizplus · Accepted Answer

The force can be calculated using Newton's second law, $ F = \frac{\Delta p}{\Delta t} $, where $ \Delta p $ is the change in momentum and $ \Delta t $ is the change in time. The change in momentum, $ \Delta p = m \Delta v = 0.43 \, \text{kg} \times 8 \, \text{m/s} = 3.44 \, \text{kg} \cdot \text{m/s} $. Thus, $ F = \frac{3.44}{0.04} = 86 \, \text{N} $.

When a 430-G Soccer Ball Is Kicked, the Impact Lasts