Newton's Laws Legacy Problem #9 Guided Solution

In Part A of this question we are asked to calculate the net force required to accelerate a 540 kg car from 0 to 27 m per second in 10 seconds. There are four items that are given here. There is a m equal 540 kg, there is a V0 equals 0, a Vf equals 27 m per second, and a t equals 10 seconds, and there is one unknown F net equal question mark. In any problem that I solve I am always going to read it carefully and identify known information just like I did there. I am going to express it in terms of variables and equations that I am using. Now what I am asked to find is net force, so I need to think how can I find F net from these four pieces of information. The immediate equation that jumps to my mind is that F net equals ma. The a is not given here though, the 27 is an a, I can tell it is not a by looking at the units. 27 is a final velocity and it is also a velocity change. What I know about a is that it is the rate of change of the velocity and it is found as a delta V over t. So the velocity is changing by 27 in 10 seconds, that means the acceleration is 27 divided by 10 or 2.7 m per second per second. Now if I take that 2.7 m per second per second and I multiply it by my mass, I am going ma is equal to the net force. Once I have done that for my ultralight car, I can repeat the same process for my Ford Expedition. The only difference is my Ford Expedition happens to be a much more massive car. Four times the mass in fact, and with four times the mass it is going to probably require four times the net force. You do the calculations and see what you get. One thing, kind of a take home concept that comes out of this is now you understand when you look at this, why SUVs are not very fuel efficient. Look at the force required to spin those wheels to get that car going from zero to 60 miles per hour and that force comes from burning gasoline.