A truck covers 40 meters in a 8.50 seconds while smoothly slowing down to a final velocity of 2.80 meters per second. Perform the following tasks:

a) find the trucks original speed
b) find its acceleration

Respuesta :

 s = (v-u)/2 * t, where v is the final velocity, u is the initial velocity, s is the displacement and t is the time. 

40 = (v-2.8)/2 * 8.5 
4.71 = v-2.8/2 
9.41 = v- 2.8 
v = 12.2 m/s 

v^2 = u ^2 +2as where v is the final velocity, u is the initial velocity, a is the acceleration and s is the displacement. 

12.2^2 = 2.8^2 + 2a(40) 
80a = 12.2^2 - 2.8^2 
80a = 148.84 - 7.84 
80a = 141 
a = 1.7625m/s^2