This is from the 2014 F=ma exam:
The maximum torque output from the engine of a new experimental car of mass m is τ. The maximum rotational speed of the engine is ω. The engine is designed to provide a constant power output P. The engine is connected to the wheels via a perfect transmission that...
If you disregard the friction of the water, isn't the water stationary? Also, if the water freezes, the bob has to expand right? since the period of a pendulum is 2pisqrt(l/g), there would be no difference. However, if the bob expands, that would slightly change l.
Oh... I see! Thanks! Now, can you answer the question of why F has to always equal 10? Can't you simply apply any force you want while lifting the object? (the math is in post 18.
In actuality, I did read the other post. I guess I need to be a little for clear with my question.Although Ken G said that -deltaU is for a single conservative force, consider a push to the right 1 meter. of an object resting on the table. There is no change in potential energy, but there is...
Oh wait... Yeah! I forgot that potential is for a specific force. Can you explain to me specifically in what cases -deltaU and deltaKE gives you the work of a specific force and when it gives you total work? Also, why must F be 10. Can't you just apply any force to the object you are lifting...
Firstly, since the work is 10, W=F(gravity)*x+F(force)*x=>10=-10+F, so isn't F=20.
If this is so, isn't it possible to choose the magnitude of the force you apply to the object? Why does the force HAVE to be g+10?
Sorry if I am being rally naive about this topic.
Yes. However, what if the final velocity is not 0. Then the extra KE would just cause a bigger final velocity which won't influence the PE. Thus, even if you have extra KE, the work still should be 10.
Oh... since Ui would be 0 and Uf =Ug+UF=0. Ok! So for W=KE, if we knew the individual deltaKE for the force, it would be 10. I have one last question. W=Fx also. Thus, assuming F is constant, W done by the force would be W=F*1=F. Thus, work depends on F. However, W=-deltaU=10 gives us that it is...