Force

An object's motion changes

• when the forces acting on the object remain balanced.

• only if the object is at rest when a force acts upon it.

• when there are no forces acting upon it.

• only when a nonzero net force is applied to the object.

Four basic forces act on an airplane while in flight: lift, weight, drag, and thrust. These four forces and their directions are indicated below.If the thrust acting on an airplane is greater than the drag, then

• the airplane will accelerate backward.

• the weight will be greater than the lift.

• the lift will be greater then the weight.

• the airplane will accelerate forward.

The image below shows a force of 10 N being applied to an object. The force is being applied toward the right, so the object is accelerating to the right. No other force is acting on the object.

Examine the image. Then, answer the question that follows.

• The object will begin moving toward the left, and it will move at a faster speed.

• The object will continue moving toward the right, but its rate of acceleration will decrease.

• The object will begin moving toward the left, and it will move at a slower speed.

• The object will continue moving toward the right, and its rate of acceleration will increase.

A speedboat is moving at a constant speed, and the force propelling it forward is balanced by the force of the water pulling it backward. But suddenly a wave strikes it from the side with a force of 500 newtons.When the wave hits the boat,

• a net force of 4,000 N will act on the speedboat.

• the speedboat's direction of motion will change.

• a net force of 8,000 N will act on the speedboat.

• the forces acting on the speedboat will stay balanced