Formulas
Formula for momentum
What is m*V
(Mass times Velocity)
This part of a car is designed to crumple during a crash so less force reaches passengers.
What is a crumple zone?
A 1,000 kg car moving at 20 m/s collides with a parked car. Before the collision, this quantity of the moving car is conserved in the system.
What is momentum?
Driving faster than the speed limit reduces reaction time and increases stopping distance. This dangerous behavior is called this.
What is speeding?
A 1,000 kg car travels at 15 m/s. Using the equation below, this is the car’s momentum.
p=mv
What is 15,000 kg·m/s?
Formula for Force
F= m*△V / △T
This safety device keeps passengers from continuing forward because of inertia during a sudden stop.
What is a seat belt?
Two cars collide and stick together after the crash. This type of collision is called this.
What is an inelastic collision?
Looking at a phone instead of the road while driving is an example of this unsafe driving behavior.
What is distracted driving?
A car travels 120 meters in 6 seconds. Using the equation below, this is the car’s speed.
v=d/t
What is 20 m/s?
Formula for change in time
△T=m*△V/F
These inflate during a collision to increase stopping time and reduce force on passengers.
What are airbags?
In any closed system, the total momentum before a collision equals this after the collision.
P before=P after
What is the total momentum after the collision?
Rain, snow, and ice can make roads slippery and reduce this between tires and the road.
What is friction or traction?
A 2,000 kg truck accelerates at 3 m/s². Using the equation below, this is the force acting on the truck.
F=ma
What is 6,000 N?
Elastic Collision Equation
m1-start*V1-start+m2-start*V2-start=m1-end*V1-end+m2-end*m2-end
Driving at lower speeds before a crash reduces this quantity, making collisions less severe.
What is momentum?
Two bumper cars collide and bounce apart without sticking together. This type of collision is most like this.
What is an elastic collision?
Following another car too closely can lead to rear-end crashes. This unsafe driving habit is called this.
What is tailgating?
Before a collision, two cars in a closed system have a total momentum of 25,000 kg·m/s. Using the equation below, this is the total momentum after the collision.
Pbefore=Pafter
What is 25,000 kg·m/s?
Inelastic colission equation formula
m1-start*V1-start+m2-start*V2-start=(m1-end+m2-end)*Vend
This modern car safety system warns drivers or gently steers the vehicle back if it begins drifting out of its lane.
What is lane assist?
A 1,500 kg SUV moving east collides with a smaller car. Investigators calculate the motion after the crash using this physics principle.
What is conservation of momentum?
A driver changes lanes without seeing another vehicle beside them because the vehicle is in this hard-to-see area.
What is a blind spot?
A passenger experiences a force during a crash for 0.2 seconds. An airbag increases the stopping time to 0.8 seconds. According to the equation below, this happens to the force on the passenger.
F△t=m△v
What is the force decreases?