There are 5 variables in the equation
v = final velocity,
u = initial velocity,
s = displacement,
a = acceleration,
t = time
You should be able to solve problems using equation about.
1. A cyclist accelerates uniformly at 1.2 ms-2 in 10 s from rest. What is his displacement at this time?
- Rest mean zero velocity !!
- You need to know 3 variables to find out the required quantities .
u = 0 ms-1
a = 1.2 ms-2
t = 10 s
v = ? ( since v is not given you are unable to calculate s using equation 1, 2, 4 and 5)
substitute all given information into equation 3
s= ut+ 1/2 at2
s= (0) (10) + 1/2 (1.2) (10)2
2. A car approaches a traffic light at 15m/s. The traffic light turns red and the driver applies the brakes at the distance of 25 m from the junction and decelerate at 5 ms-2. Can the car come to complete stop before reaching the stop line at the traffic light? (ans : yes)
- remember to insert the negative sign (-) for decelerate
*learn more in http://en.wikipedia.org/wiki/Equations_of_motion