4.7 Further Applications of Newton’s Laws of Motion

Two people push on a boulder to try to move it. The mass of the boulder is 825 kg. One person pushes north with a force of 64 N. The other pushes west with a force of 38 N. Predict the magnitude of the acceleration of the boulder. Assume that friction is negligible.

A flea jumps by exerting a force of $1 . \text{20} \times \text{10}^{- 5} \text{ N}$ straight down on the ground. A breeze blowing on the flea parallel to the ground exerts a force of $0 . \text{500} \times \text{10}^{- 6} \text{ N}$ on the flea. Find the direction and magnitude of the acceleration of the flea if its mass is $6 . \text{00} \times \text{10}^{- 7} \text{ kg}$. Do not neglect the gravitational force.

When starting a foot race, a 70.0-kg sprinter exerts an average force of 650 N backward on the ground for 0.800 s. (a) What is his final speed? (b) How far does he travel?

A basketball player jumps straight up for a ball. To do this, they lower their body 0.300 m and then accelerate through this distance by forcefully straightening their legs. This player leaves the floor with a vertical velocity sufficient to carry the player 0.900 m above the floor. (a) Calculate the player's velocity when they leave the floor. (b) Calculate their acceleration while they are stra…

Repeat the exercise for a shell fired at an angle $\text{10}.\text{0}º$ from the vertical.