F=ma problem, I feel retarded because I can't get it

[phx1]

Seriously I feel so stupid because I can't get the answer to the second part of the problem, what am I doing wrong?

Homework Statement

2 parts to the problem:

An empty truck whose mass is 1500 kg has a maximum acceleration of 1.4 m/s^2 . What is the maximum force that accelerates the truck? ______N

What is the maximum acceleration when it is carrying a 500 kg load? (hint: same force, but new total mass) ______m/s^2

Homework Equations

F=ma

The Attempt at a Solution

This is for a web based quiz and I got the first part right, it's obviously 2100 N, so then I figured: ok, so to find the acceleration using the same force just solve for a, therefore it should be 2100 N/500 kg, which gives me an answer of 4.2 m/s^2. It's telling me the 2100 N is correct, but not the 4.2 m/s^2 ... what am I doing wrong or not taking into consideration? It's so easy I'm just missing it...

 

[Carid]

Force = TOTALmass * acceleration

What is the TOTALmass

 

[nlightner]

First of all, it's important to remember that everyone learns at their own pace and it's completely normal to struggle with certain concepts. It's important to not be too hard on yourself and to keep trying.

In this problem, you are correct that the maximum force that accelerates the truck is 2100 N. However, the second part of the problem is asking for the maximum acceleration when the truck is carrying a 500 kg load. This means that the total mass of the truck and load is now 1500 kg + 500 kg = 2000 kg.

To find the maximum acceleration, you need to rearrange the equation F=ma to solve for a. This gives you a=F/m. Plugging in the known values, you get a=2100 N/2000 kg, which gives you an answer of 1.05 m/s^2.

So, the maximum acceleration when the truck is carrying a 500 kg load is 1.05 m/s^2, which is half of the maximum acceleration when the truck is empty. This makes sense because the same force is acting on a larger mass, resulting in a smaller acceleration.

I hope this explanation helps and don't be discouraged, you're on the right track! Keep practicing and asking for help when needed.