A car enters the freeway with a speed of 7.1 m/s

Question

A car enters the freeway with a speed of 7.1 m/s and accelerates uniformly for 3.3 km in 4.3 min. How fast is the car moving after this time? Answer in units of m/s.

Answer 1

Initial velocity vi = 7.1 m/s

Distance  d = 3.3 km = 3300 m

Time t = 4.3 minutes = 4.3 x 60 = 258 s

Final velocity vf = ?

 

Which equation of motion connects all four vi, d, t , and vf ?

d = average velocity x time

 

What is the average of vi and vf? (vi + vf)/2

 d = t x (vf + vi)/2

 

Substitute the values and solve for vf.