Physics Quiz 5

What is inertia?

Property of matter that explains an object’s tendency to maintain its state of motion. Resistance to change in motion

What is momentum?

measure of inertia of an object that is in motion

What does inertia depend on

mass

How do we measure inertia?

mass is used - the more mass an object has, the greater its inertia and the more it resists changes in motion

Unit to measure inertia

kg-m

What two quantities does momentum depend on?

mass (scalar) and velocity (has direction)

Is momentum a vector?

yes

How does an object’s momentum change when the dependent quantities change?

the direction of an object’s momentum will always be the same as the direction of its velocity

unit used for momentum

kg-m/s \[mass (kg) velocity (m/s)\]

imagine you are asked to push two boxes that have been placed on an icy surface (no friction). One is empty and the other is full of paper. What could you do to identify the difference between these boxes without lifting or opening them.

1. By pushing them whichever one is harder to push since there is no friction will be the heavier one so the one full of paper. (Everything would slide to the lowest point )


1. Their change in momentum

What does Newton’s first law tell us about the motion of objects that are experiencing balanced forces?

1. Newton’s 1st Law says that when an object experiences balanced forces (all the forces in all directions add to 0), it will continue moving at a constant speed in a constant direction (aka constant velocity).


1. Unbalanced forces cause objects to change their motion (speed up, slow down, change direction, or some combination of those).

p in p=mv

momentum

m in p=mv

mass

v in p=mv

velocity

how is momentum calculated?

by multiplying the mass of the object by its velocity.

What is the momentum of a 25 kg dog, running at a velocity of 5 m/s South?

125 kg∙m/s South