Forces Interactions

Forces Interactions

Forces

• A force is any push or pull on an object

• A force can be balanced or unbalanced

• All forces acting on an object is known as the Net Force

Balanced Force

• The Net Force equals 0

• Does not cause a change in motion

• 
  

Unbalanced Force

• Net Force is greater than 0

• Causes a change in motion

Multiple Choice

What is the net force of an object that is being pulled in opposite directions with equal strength?

• 0N

• 10N

• 5N

Multiple Choice

Is this object under balanced or unbalanced forces?

• balanced

• unbalanced

Multiple Choice

Find Net Force

• 17 N left

• 20 N left

• 20 N right

• 17 N right

Speed

• The rate at which an object is able to move

• speed=distance/time

• Common unit of speed is m/s (meters per second)

Mass

• The amount of matter in an object

• measured in grams and kilograms

Speed and Mass

• Indirectly proportional

• the more mass an object has the more force required to move it at the same speed as a less massive object

• If force stays constant and mass increases then speed decreases

• If force stays constant and speed increases then mass decreases

Graph relating Mass and Speed

Mass is on the X axis and speed on the Y axis.

Notice the curve and how as you increase along 1 axis you decrease along the other.

Multiple Choice

A object grows in mass as it flies. If its force stays the same what happens to the speed of the object?

• It stays the same

• It increases as well

• It decreases

Multiple Choice

If the object wanted to maintain the same speed as it had when it was smaller it would need to...

• decrease its force output

• increase its force output

Kinetic Energy (KE)

• The energy an object has in motion

• Is proportional to both speed and mass

• If speed increases and mass is constant KE increases

• If mass increases and speed stays constant then KE increases

• If both mass and speed increase so does KE

Kinetic Energy and Mass

The straight line means that whatever happens to Mass (X axis) happens to KE (Y axis)

Kinetic Energy and Speed

Notice the curve. The curve shows that whatever happens to the square of speed (x axis) happens to the KE (y axis).

This creates an exponential increase. Exponential meaning a greater and greater increase with each change.

Multiple Choice

How can you maintain the kinetic energy of a system if the system gains mass?

• Reduce the speed at which it moves.

• Increase the speed at which is moves.

• Add another object to counteract its motion.