1.2 Lesson: The first law of motion

Inertia is the tendency of any object to maintain its:

• Acceleration

• Shape

• Velocity

• Position

An object has a velocity of 7 m/s east. Due to the object's inertia it will tend to:

• continue moving at 7 m/s east

• slow down but continue in an easterly direction

• stop

• maintain its speed but slowly change direction

Due to inertia, a particular object has a tendency to maintain it's a velocity of 0 m/s.

Which best describes the object's current state of motion?

• It is at rest

• It is moving slowly in a straight line, slowing down

• It is moving slowly in a curving trajectory

• It could be any of the above three answers

When you throw a stone up in the air, it naturally falls back down to the Earth. This is because of its inertia.

• True

• False

Which is Newton's first law of motion?

• Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that by forces impressed on it.

• Force is equal to change in momentum (mV) per change in time. For a constant mass, force = mass x acceleration

• For every action, there is an equal and opposite re-action

Which of the following objects have constant velocity, or zero acceleration?

• A basketball slowing down as it rolls in a straight line

• A train travelling at a steady speed on a straight track

• A bungee jumper falling

• A car accelerating out of a driveway

Which of the objects from the previous question have net forces acting on them?

• A sizzling pizza sitting on a plate

• A tennis ball being thrown from one person to another

• A train travelling at a steady speed on a straight track

Inertia is a type of force.

• True

• False

An object's inertia means that if it is moving in a straight line it requires a force to keep it going at a constant speed.

• True

• False

What might an object do when there are no forces acting on it?

• Start moving

• Remain at rest

• Stop moving