A driver of a car traveling at 15.0 m/s applies the brakes, causing a uniform acceleration of -2.0 m/s squared. How long does it take the car to accelerate to a final speed of 10.0 m/s? How far has the car moved during the braking period?

a) 2.5secs

b) 31.25m

Explanation:

a) From the question, we are given;

Initial speed u = 15m/s

Final speed v = 10.0m/s

Acceleration =-2.0m/s²

Required

How long it takes take the car to accelerate (Time t)

Using the equation of motion

v = u+ at

10 = 15+(-2)t

10 = 15-2t

10-15 = -2t

-5 = -2t

t = 5/2

t = 2.5secs

Hence it takes the car 2.5secs to accelerates.

b) We are to find distance S

Using the equation

S = ut + 1/2at²

S = 15(2.5)+1/2(-2)(2.5)²

S = 37.5-6.25

S = 31.25m

Hence the car as moved by 31.25m during the breaking period.

c) up is the direction the magnetic force is acting on the charge.