Question

Which of the following would be a situation with unbalanced forces? (1 point)
A team of players in tug of war pulling on the rope, each team with equal numbers of people pulling with equal strength
• Two people pulling on the same side of a wheelbarrow
• Two people not touching a crate that is sitting stationary
Two people of opposite sides of a big tire. One pushes the tire and one pulls it with equal force
Why is it generally easier to push a heavy object that is already moving instead of the same heavy object that is stationary (1 point)
• The force of friction on the object is different if it is stationary or not
• The force of the push on the object is different if it is stationary or not
• The force of gravity on the object is different if it is stationary or not.
• The normal force on the object is different if it is stationary or not

Answer 1

Answers:

- Situation with unbalanced forces: Two people pulling on the same side of a wheelbarrow.
Reason: their forces add in the same direction, producing a net (unbalanced) force that will accelerate the wheelbarrow.

- Why it's easier to push a heavy object that's already moving: The force of friction on the object is different if it is stationary or not.
Reason: static friction (must be overcome to start motion) is generally larger than kinetic friction (while moving), so less force is needed to keep it moving than to start it.