CP Forces Review

When all individual forces acting on an object are balanced, it is the natural tendency of an object to ____.

• eventually stop

• accelerate

• either speed up, slow down or keep the same speed

• keep its velocity constant (either at a zero or non-zero value)

• either stay at rest or come to a rest position

The law of inertia (Newton's first law) applies ____.

• only to objects that are not moving

• to moving objects

• to both moving and nonmoving objects

A sled slides down a hill, reaches the level surface and eventually comes to a stop. The fact that the sled ultimately stops is best explained by ____.

• the presence of inertia causes it to stop

• the natural tendency of any object is to ultimately stop

• an unbalanced force would be required to keep the sled moving forward at constant speed

• the presence of an unbalanced force (e.g., friction) can cause a moving object to stop

For each object, determine if it could be moving to the right at a constant speed with the given forces present?

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

A sprinter in track is able to progress towards the finish line due to the marvels of Newton’s third law. Identify the two action-reaction force pairs that are responsible for this running action.

• The ground pushes forward on the sprinter’s shoes.

• The sprinter pushes herself forward using her leg muscles.

• The sprinter’s shoes push backward upon the ground.

• The left leg moves forward as the right leg moves backward and vice versa.

• The force of gravity pulls the sprinter toward the track.

Late one night, an unfortunate bug collides with the windshield of a fast-moving bus. The force of the bug on the bus is _____ the force of the bus on the bug; the resulting acceleration of the bus is _____. the bug's acceleration​ (a)   ​

• equal to, less than
• less than, equal to
• greater than, less than
• equal to, greater than
• equal to, equal to
• less than, greater than

Tags

NGSS.MS-PS2-1

An object is moving along a level surface with a constant velocity. The net force acting upon the object is _____.

​ (a)  

• zero
• in the direction of the motion
• opposite the direction of the motion

The diagram represents the forces acting on an upward-moving object.  Each arrow represents a force; the length of the arrow represents the strength of the force. The object is _____.

• speeding up

• slowing down

• maintaining a constant speed

Tags

NGSS.MS-PS2-2

The diagram at left represents the forces acting on an upward-moving object.  Each arrow represents a force; the length of the arrow represents the strength of the force. The forces are _____.

• Balanced

• Unbalanced

The motion of an object is represented by the following velocity-time graph. The object is ____.

• speeding up

• slowing down

• keeping a constant speed

Tags

NGSS.MS-PS3-1