- A woman riding a bicycle collides head-on with a parked
school bus. Which object feels greater force?
Here’s How to Crack It
Newton’s third law states that the force exerted by the bus on the woman/bike will
be equal in magnitude to the force that the woman/bike exerts on the bus. What is
different is the effect of the force. Since Fnet = ma, the bus (with larger mass) will
experience a smaller acceleration than the woman on the bike.
Slow Down: A Momentum Recap
The three laws we’ve just covered are the foundation to many other
concepts, so let’s sum them up before moving on.
Newton’s First Law- Moving objects keep moving
- Resting objects keep resting
- Law of Inertia: Objects naturally resist change in their velocities.
- The measure of inertia is mass.
Newton’s Second Law
Fnet = ma
Forces are vectors, measured in Newtons (N).
Newton’s Third Law
Action-reaction pairs are equal in magnitude but opposite in direction, so
F1-on-2 = F2-on-1.