ME 274: Dynamics: Chapter 14.4

[@Egrom]

At the sports car problem: In the sum of the forces in the X-direction, it should be MINUS 2000*g*sin(5.711) in the left hand side of the equation, not positive

[@ColinSelleck]

Good catch, Andreas. The answer Fc = 3619 N is correct.

[@anematix7178]

At 8:19, you solved for T and figured it to be 320.3, but in your power equation for force shouldn't you use 2 times T because there are 2 cables? the 320.3 would be the force from just one of them..?

[@ColinSelleck]

No. The motor only has one cable with tension T.

[@moh4686]

Thanks a lot. It was really useful

[@thenatmann1]

not bad colin! you do an excellent job explaining the proper methods to carryout. I've been having a rough time with dynamics and you are definitely helping to solve some pretty difficult problems. My current dynamics professor is terrible in comparison..

[@ColinSelleck]

Thanks!

[@anematix7178]

At 12:00 when calculating power output. For the force why did you include only Fc... Shouldn't it be Fc - X component of weight? And if the case is that you multiply only the force acting in the same direction as the velocity, how come in the first problem you multiplied the tension with the velocity? Tension was acting upwards while velocity was going downwards.

[@ColinSelleck]

Fc was calculated using the X component of the weight. So Fc is what the car's engine needs to produce to overcome the incline and accelerate the car. This is why only Fc is used.

[@moh4686]

The P avg, why we divided the V with 2? in 12:15

[@ColinSelleck]

+Mohammed Saad I divide by two to get the average speed of the car.

[@alyncastanogonzalez3628]

10:35 why did you used sen? shouldn´t i use cos? or it depends?

[@ColinSelleck]

It is sin(5.711) since the angle 5.711 is measured from the positive y axis. The angle from the positive x axis is (90 - 5.711) = 84.289, so you could have used cos(84.289). Same thing.

[@abelalfeuz5860]

why acceleration 8.33??...is it true?

[@ColinSelleck]

At 11:20 I put a note saying the acceleration is 0.833 m/s^2.