Answer to Question #309591 in Physics for lyn

Question

Motion along a Line with Constant Acceleration. 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) the change in speed occurs between t = 10.0 s and t = 12.0 s

$$\Delta v=a\Delta t\\ =-\rm 2.0\: m/s^2*2.0\: s=-4.0\: m/s$$

(b) the the speed when the stopwatch reads 12.0 s

$$v_2=|v_1+\Delta v|\\ =|\rm 1.0\: m/s-4.0\: m/s|=3.0\: m/s$$