April 9, 2014 10:32 pm at 10:32 pm #612558
I am trying to learn basic Physics and am learning about applying Newton’s Laws in 2 and 3 dimensional motion. I really know anyone who knows this stuff and I know that a lot of smart people read the stuff here sometimes.. I am hoping maybe someone can help me out:
Did I do this correctly? If not where am I wrong?
Thanks!!April 9, 2014 11:45 pm at 11:45 pm #1011372
What is the mass of you car? That is a major factor. According to netons 3rd law, every thing has opposite and equal force. The reason why you don’t fall through the floor is because of this opposite and equal force or better known as the NORMAL FORCE. To fid your normal force, you multiply your mass*gravity (mg). So that is what you are missing the mass of the car.April 10, 2014 12:16 am at 12:16 am #1011373
Right?April 10, 2014 1:15 am at 1:15 am #1011374–Participant
I got 27.3 MPH but that’s because I started out by converting everything to SI units. I think your error is in approximation too early in the equation.April 10, 2014 1:27 am at 1:27 am #1011375
Your righ I over thought the example.April 10, 2014 1:28 am at 1:28 am #1011376
I’m not sure I understand what you mean…April 10, 2014 1:51 am at 1:51 am #1011377
A 4.20*10^3-kg rocket takes off from the moon where the acceleration due to gravity is 1.60 m/s^2 by exhausting 8.20 kg of gas per second at a speed of 2.20 103 m/s. Determine the acceleration of the rocket.April 10, 2014 3:54 am at 3:54 am #1011378
If you mean it went from 2.2 m/s to 103 m/s while it burned gas for 1 second. Then it’s accelerating at 100.8 m/s. I’m not sure I understood your question thoughApril 10, 2014 8:12 am at 8:12 am #1011379–Participant
I’m not sure I understand what you mean…
I went back and looked at what you did and came up with the followingApril 10, 2014 1:06 pm at 1:06 pm #1011380
000646, it is supose to be 2.20*10^3 m/sApril 10, 2014 1:39 pm at 1:39 pm #1011381Avram in MDParticipant
Dash is correct – you have to make sure all of your units line up, which is best done by showing all work.
Newton’s Second Law: F = ma
The gravitational acceleration is g = 9.8 m/s
Centripetal acceleration is a = v^2/r
So to keep that car on track, you want to balance the centripetal acceleration with gravitational acceleration, so: 9.8 = v^2/r
Your r is known: 50ft, which is 15.24m, so v^2 = 9.8 * 15.24, and v = sqrt(9.8 * 15.24) = 12.22 m/s.
Converting 12.22 m/s into mph and you get 27.3.April 10, 2014 2:28 pm at 2:28 pm #1011382Avram in MDParticipant
Whoops, in my above post, the units for acceleration should be m/s^2, not m/s 🙂April 10, 2014 2:33 pm at 2:33 pm #1011383
Dash and Avram in Md
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