A single object usually has several forces acting on it at once. Gravity pulls it down, the floor pushes it up, an engine drives it forward, and friction drags it back. The single force that has the same effect as all of these combined is called the resultant force.
If forces are balanced, the resultant force is zero, and the object stays at rest or continues at a steady speed in a straight line. If forces are unbalanced, the resultant force is not zero, and the object accelerates.
The resultant force is the single force that has the same effect as all the forces acting on an object.
A non-zero resultant force always produces an acceleration in its own direction.
Set the forces acting on the block and read off the resultant. When the arrows cancel, the resultant is zero and the motion does not change. When one side wins, the block accelerates that way.
Four quick checks on combining forces and what a resultant does. Each correct answer earns XP and lights this skill on your star map.
The resultant force on an object is...
A box is pushed right with 10 N while friction pushes left with 4 N. The resultant force is...
If the resultant force on a moving object is zero, the object...
An unbalanced (non-zero) resultant force always causes...
When forces act along the same straight line, add those pointing one way and subtract those pointing the other. The resultant points in the direction of the larger total, and its size is the difference.
A block is pulled to the right by a force of 12 N, while friction of 4 N acts to the left. Find the resultant force and state the resulting motion.
The greatest trap is believing an object needs a forward resultant force just to keep moving. It does not. A car cruising at a steady 30 m/s has a resultant force of zero, because the engine push balances the air resistance. A forward resultant force is only needed to accelerate and change the speed, not to maintain it.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 1.
Two forces act on a trolley along the same straight line: 18 N forward and 11 N backward. The resultant force is...
A car travels along a straight, level road at a steady 25 m/s. The resultant force on it is...
A resultant force acts on a moving object in the direction opposite to its motion. The object will...
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