Question

part b
you have an old - style reel lawn mower at home. no engine! you need to cut the grass but also finish in time to watch your favorite tv show. how would you apply newtons second law of motion here?

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: Recall 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 Part B

When using a reel lawn mower, to finish cutting grass faster (increase acceleration $a$), you can apply more force $F$ if the mass $m$ of the mower is constant. Or, if possible, reduce the mass of the mower (e.g., remove any unnecessary attachments) to increase the acceleration for the same applied force.

Step3: Analyze Part C (small car)

When pushing a small car, initially when it was not moving, a large force was needed to overcome static friction. As more friends helped, the net - force $F$ increased. According to $F = ma$, with an increase in $F$ and a relatively constant mass $m$ of the small car, the acceleration $a$ increased, causing the car to start moving and rev up.

Step4: Analyze Part C (large SUV)

A large SUV has a much larger mass $m$ compared to a small car. To achieve the same acceleration $a$ as the small car, a much larger net - force $F$ is required according to $F = ma$. So, more people or a stronger force source would be needed to move the large SUV.

Answer:

In Part B, apply more force or reduce mower mass to increase acceleration. In Part C for the small car, more friends increased the net - force leading to acceleration. For the large SUV, due to its large mass, a much larger net - force is needed to achieve the same acceleration as the small car.