Question

part c
you and your friends are going on a picnic in a very small car. on your way, the car breaks down and you try to push it to get it to move but in vain. you ask your friends to help you and the car starts moving and revs up. how are you and your friends applying newtons second law of motion here? what if the car you were traveling in was a large suv?

Explanation:

Step1: State Newton's second law

Newton's second law is $F = ma$, where $F$ is the net - force, $m$ is the mass and $a$ is the acceleration.

Step2: Analyze pushing the car

When trying to push the car to move, the force $F$ applied by you and your friends is related to the mass $m$ of the car and the resulting acceleration $a$. Initially, when you push alone, the force may not be enough to overcome the static friction and move the car (so $a = 0$ as $FF_{s - max}$, the car starts moving.

Step3: Analyze different car masses

For a small car, it has a relatively small mass $m$. According to $F = ma$, for a given force $F$, a smaller $m$ results in a larger acceleration $a$. For a large SUV, it has a larger mass $m$. To achieve the same acceleration $a$ as the small car, a much larger force $F$ is required. When the car revs up, the engine provides a force. The acceleration of the car depends on the net - force (engine force minus resistive forces like friction) and the mass of the car according to $F_{net}=ma$.

Answer:

When pushing the car, the more people helping, the greater the applied force, and if it exceeds the maximum static - friction force, the car moves. According to Newton's second law $F = ma$, a small car has a smaller mass and is easier to accelerate with a given force compared to a large SUV which has a larger mass and requires a much larger force to achieve the same acceleration. When the car revs up, the acceleration is determined by the net - force (engine force minus resistive forces) and the mass of the car using $F_{net}=ma$.