1.

A driver wanted to test the braking system of his car. He traveled at 30 m/s, and after applying the brakes, came to a stop in 3.5 s. Calculate the car's acceleration and the distance necessary to the car to stop.

 Δt = 3.5s

 ⇀v1 = 30 m/s

 ⇀v2 = 0 m/s2

 ⇀a = ? 

Equation: V2=⇀v1 +⇀a • Δt 

Rearranged:⇀a = v2-⇀v1 / Δt

 ⇀a = 0 m/s - 30 m/s / 3.5s

 = -8.60 m/s2 

Significant Figures = 3 Therefore the driver was accelerating at -8.60 m/s2 relative to the direction in which she was originally traveling. (We could also say the driver was decelerating at a rate of 8.60 m/s

2)

A truck is traveling at 108 km/h. Because of an accident on the road, it has to come to a stop. If the truck can decelerate at a constant 4.5 m/s2, how far does it travel before it stops?

108km/h = 30 m/s

 V1 = 30 m/s

 V2 2= 0 m/s2 

A = -4.5m/s2 

Equation: V22= V1 2+ 2a • Δd

 Rearranged: Δd = V22- V1 2/ 2a 

Δd = 0m/s2- 30 m/s2/ 2(-4.5m/s)

 = 100m Significant 

Figures: 1 Therefore it travels 100 meters before it stops.