If you pull something at a constant velocity is the total force equal to zero
Favorites|Homepage
Subscriptions | sitemap
HOME > > If you pull something at a constant velocity is the total force equal to zero

If you pull something at a constant velocity is the total force equal to zero

[From: ] [author: ] [Date: 11-11-21] [Hit: ]
Momentum is mass x velocity (P = mv), and the velocity is constant (given), so unless the mass of the object changes as it moves, the momentum is constant too.No change in momentum over time means dP/dt = 0, means no net force.......
Is the total force eqaul to zero or is it greater than zero?

-
The NET force is 0. Friction = applied force.

-
Yep. Force is that which causes acceleration, so if it's not accelerating (v = constant) there's no net force.

More formally, force is the change in momentum over time, that is, the time-derivative of momentum (F = dP/dt). Momentum is mass x velocity (P = mv), and the velocity is constant (given), so unless the mass of the object changes as it moves, the momentum is constant too. No change in momentum over time means dP/dt = 0, means no net force.

This is a vast oversimplification, of course. I don't know jack about REAL physics. If the total force were really equal to zero, the thing you're pulling would go winging out into space in a straight line as it departed from the curve of the earth or something. But in this inertial reference frame, yeah, that's how it works.

-
Technobuff's answer is correct, but you have to assume with it that the mass of the object isn't changing.
Suppose you are pulling on a cart and sand bags are continuously thrown into the cart from the sidewalk. If you want to keep a constant velocity, you will need to pull harder than the frictional force, so you need a non-zero net force!
This can be seen from:

F = dp/dt = d(mv)/dt = m dv/dt + v dm/dt .

With a constant velocity, dv/dt = 0. Usuallly, with constant mass, we conclude that the total force F is zero. But you see that if the mass is changing, a constant velocity requires a nonzero net force:

F = v dm/dt .

-
It's 0.

According to Newton's 2. law, if the object has certain mass m, and force acting on it is ≠ 0, that the object would have constant acceleration of F/m.
1
keywords: velocity,is,pull,at,zero,you,force,something,If,equal,total,constant,to,the,If you pull something at a constant velocity is the total force equal to zero
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .