wunder beta➡️ Resultant Forces
Real objects feel many forces at once. Learn to add them up into a single resultant force — and predict exactly how an object will move.
What you’ll learn
- Adding Forces TogetherDefine the resultant force and combine forces acting in the same or opposite directions.Objects usually feel several forces at once. Combining them into one gives the resultant, or net, force, which has the same effect as all of them together. Forces in the same direction add (5 N + 3 N = 8 N); forces in opposite directions subtract, with the resultant pointing the way of the bigger force (5 N − 3 N = 2 N).
- Balanced ForcesExplain that balanced forces give a zero resultant and do not change motion.When opposite forces are equal, they cancel and the resultant force is zero — these are balanced forces. A zero resultant means motion does not change: a still object stays still, and a moving object keeps the same speed and direction. Anything with a non-zero resultant is unbalanced.
- Unbalanced ForcesExplain that an unbalanced resultant force changes motion in its own direction.Unbalanced forces leave a resultant force that is not zero, and this is what changes an object's motion — speeding it up, slowing it down, or turning it. The change always happens in the direction of the resultant force. For example, 6 N right and 2 N left give a 4 N resultant to the right, so the object accelerates that way.
Questions this course answers
What is the single overall force from combining all forces on an object called?
Combining every force on an object gives the resultant force, also called the net force.
Two forces of 5 N and 3 N push a box in the same direction. What is the resultant force?
Forces in the same direction add together: 5 N + 3 N = 8 N.
A box is pulled 5 N right and 3 N left. What is the resultant force?
Opposite forces subtract, and the resultant points the way of the bigger force: 5 − 3 = 2 N to the right.
If the forces on an object are balanced, the resultant force is...
Balanced forces cancel each other exactly, leaving a resultant force of zero.
A car cruises at a steady speed in a straight line. What is true about the forces?
A zero resultant force means motion does not change, so a steadily cruising car has balanced forces.
A trolley feels 6 N right and 2 N left. What happens?
The resultant is 6 − 2 = 4 N to the right, and an unbalanced force changes motion in the direction of the resultant.
Grounded in trusted sources
- BBC Bitesize
- Britannica
- The Physics Classroom
- NASA
Every Wunder lesson is built from real, reputable sources — never invented.
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