4.2 Unbalanced Forces

A car is travelling at a constant speed. Which statement describes the forces acting on the car?

• The forces acting on the car are balanced.

• The forces acting on the car are unbalanced.

A book is sitting on a table. Which statement describes the forces acting on the book?

• The forces acting on the book are balanced.

• The forces acting on the book are unbalanced.

The two cats on the see-saw have the same weight. The forces acting against the pivot of the see-saw are (a)   .

• balanced

• unbalanced

The two cats on the see-saw have the same weight. The forces acting against the pivot of the see-saw are balanced, so the see-saw will . . .

• balance in the middle.

• tip to the right.

• tip to the left.

The thrust force acting on a moving plane is greater than the air resistance acting against it. The horizontal forces are . . .

• balanced.

• unbalanced.

If the thrust force acting on a moving plane is greater than the force of air resistance acting against it, the plane will . . .

• travel at a constant speed.

• speed up.

• slow down.

If the thrust force acting on the moving plane is smaller than the force of air resistance acting against it, the plane will . . .

• travel at a constant speed.

• speed up.

• slow down.

All three cats on the see-saw are the same weight. The forces acting against the pivot of the see-saw are __________.

• unbalanced

• balanced

All three cats on the see-saw are the same weight. The forces are unbalanced. The see-saw will . . .

• tip to the right.

• tip to the left.

• balance in the middle.

A force of 5 N is acting on the block. If this is the only force acting on the block, which statement describes the resulting motion?

• The block moves to the right with a force of 5 N.

• The block is stationary.

• The block moves to the left with a force of 5 N.