Question

A car is speeding up and has an instantaneous velocity of 1.0 m/s in the +x-direction when a stopwatch reads 10.0 s. It has a constant acceleration of 2.0 m/s² in the x-direction.

(a) What change in speed occurs between t = 10.0 s and t = 12.0 s?

(b) What is the speed when the stopwatch reads 12.0 s?

Answer 1

(a) What change in speed occurs between t = 10.0 s and t = 12.0 s?

$$\Delta v=at\\ =\rm 2.0\: m/s^2*2.0\:s=4.0\:\rm m/s$$

(b) What is the speed when the stopwatch reads 12.0 s?

$$v_2=v_1+\Delta v\\ =\rm 1.0\: m/s+4.0\: m/s=5.0\: m/s$$