Equal forces in opposite directions give zero net force. With no friction, that preserves velocity: a still cart stays still, and a moving cart keeps the same speed and direction. These two trials use identical 2 kg carts and the same forces; only their starting velocities differ. Press Play to compare four seconds. Then make the right push stronger and watch the one-second position gaps grow.
Forces, motion and energy · Discover & try
Can balanced forces act on a moving object?
Reading level 3 of 5 · IndependentChange
Word help
Net force
The combined force after directions are taken into account. Here, equal left and right pushes cancel.
Velocity
Speed together with direction. A constant velocity means that neither changes.
Acceleration
A change in velocity over time: speeding up, slowing down or changing direction.
Watch · Try · Explain
See how it works
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Two separate 2 kg cart trials with the same constant horizontal forces. One starts at rest; one starts at 2 m/s right. Friction is excluded.
What to look for
- With equal pushes, compare cart A staying still with cart B keeping the same speed.
- Watch the clock: each dot records the cart’s position one second after the previous dot.
- Make one push stronger. How do the speed and the gaps between dots change?
Explain what you noticed
A different cart moves right while experiencing 5 N left and 5 N right, with no other horizontal force. What happens next?
Keep this idea: Balanced forces preserve motion: a still cart stays still, and a moving cart keeps the same speed and direction.
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Source material checked 2026-10-29. Explanations and activities by Nepedia. Source links do not imply endorsement.
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