Get Updates
Subscribe to receive instant notifications for new study materials and important updates.
According to the third law of motion when we push on an object... - Science
According to the third law of motion when we push on an object, the object pushes back on us with an equal and opposite force. If the object is a massive truck parked along the roadside, it will probably not move. A student justifies this by answering that the two opposite and equal forces cancel each other. Comment on this logic and explain why the truck does not move.
The student's logic is incorrect because the two equal and opposite forces do not cancel each other out in terms of the truck's motion.
Here's why:
Forces act on different objects: Newton's Third Law states that forces occur in pairs acting on different objects. When you push the truck, you exert a force on the truck. The truck, in turn, exerts an equal and opposite force on you. These forces do not act on the same object, so they cannot cancel each other out to determine the motion of a single object (the truck).
Why the truck doesn't move: The truck does not move because the force you exert on it is not enough to overcome the static friction between the truck's tires and the road. For the truck to move, the force you apply to it must be greater than the maximum static friction force.
In summary, the forces cancel each other between you and the truck, but the force on the truck is still present. The truck remains stationary because this applied force is less than the static friction force preventing its movement.