How Do You Calculate Initial Acceleration in Newton's Laws Problems?

[Bensky]

[SOLVED] Need help on a Newton's Laws problem :(

Homework Statement

A 56 kg ice skater holds up a large sheet of cardboard that can catch the wind and drive her (frictionlessly) across the ice. While she's moving at 0.5 m/s, a wind that is constant and horizontal for 5.0 s exerts a force on the cardboard of 2.1 N. What is the skater's initial acceleration once the wind begins to blow?

Homework Equations

f=ma
a=change in velocity/change in time

The Attempt at a Solution

I'm not sure how to find the initial acceleration. I know how to find the average acceleration though.

 

[Bensky]

Nevermind, figured it out on my own:
Just have to do: 2.1/56

>_< why did i think this was hard...

 

[ogb p]

Can someone please help?

Hello there,

It seems like you are trying to apply Newton's Second Law of Motion (F=ma) to solve this problem. In this case, the force (2.1 N) is given and the mass (56 kg) is known, so you can rearrange the equation to solve for acceleration (a).

a = F/m

a = 2.1 N / 56 kg

a = 0.0375 m/s^2

This is the average acceleration over the 5 seconds that the wind is blowing. To find the initial acceleration, you can use the equation a=change in velocity/change in time. Since the skater is initially moving at 0.5 m/s and there is no initial force acting on her, the initial acceleration would be 0 m/s^2.

I hope this helps. Keep practicing and you will become more familiar with applying Newton's Laws to solve problems. Good luck!