# Worksheet: Inertia and Newton's First Law of Motion

In this worksheet, we will practice calculating the unknown forces acting on an object so that it remains still or moves at a constant velocity.

Q1:

Three forces act on a particle, which moves with constant velocity . Two of the forces are and . Find the third force, .

• A N
• B N
• C N
• D N
• E N

Q2:

While sliding a couch across a floor, the housemates Liam and Emma exert forces and , respectively, on the couch. is of magnitude 130 N directed due north and is of magnitude 180 N directed east of north. A force is produced by the combination of the forces exerted by Liam and Emma. In evaluating the net force, assume that east corresponds to positive displacement along the and that north corresponds to positive displacement along the .

Find in component form.

• A N
• B N
• C N
• D N
• E N

Find the magnitude of .

At what angle north of east is directed?

If Liam and Emma’s housemates, Matthew and Mia, disagree with the move and want to prevent its relocation, with what combined force should they push so that the couch does not move?

• A N
• B N
• C N
• D N
• E N

Q3:

Two forces and act on an object. What force must be added to and to produce a net force of zero?

• A N
• B N
• C N
• D N
• E N

Q4:

A force is applied to accelerate an object on a smooth icy surface. When the force stops, which of the following will be true? (Assume that friction is zero.)

• AThe object’s speed becomes zero.
• BThe object’s acceleration becomes zero.
• CThe object accelerates, but in the opposite direction.
• DThe object’s acceleration continues to increase at a constant rate.

Q5:

What is Newton’s first law of motion also known as?

• Athe law of force
• Bthe law of gravitational attraction
• Cthe law of inertia
• Dthe law of action-reaction
• Ethe law of conservation of energy