Is the total force eqaul to zero or is it greater than zero?
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The NET force is 0. Friction = applied force.
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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.
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.
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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 .
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 .
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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.
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.