A car starts from rest and accelerates at a constant rate. After the car has gone 50 m it has a speed of 21 m/s. What is the acceleration of the car?

A. 4.4 m/s2
B. 2.4 m/s2
C. 0.23 m/s2
D. 5.5 m/s2

Question

A car starts from rest and accelerates at a constant rate. After the car has gone 50 m it has a speed of 21 m/s. What is the acceleration of the car?

 		A.	4.4 m/s2
 		B.	2.4 m/s2
 		C.	0.23 m/s2
 		D.	5.5 m/s2

anonymous · Answer

If you award medals, you WILL get much more attention! :)

anonymous · Answer

I do give medals to the ones that help me. @HomeschoolGrad

schrodingers_cat · Answer

Remember for a particle under constant acceleration

Vf =Vi +at

and 

Xf -Xi = 1/2(Vi +Vf)t             where 1/2(Vi +Vf) is the average acceleration

Substituting the first equation into the second for t yields

Vf^2 -Vi^2 = 2a(Xf -Xi)

Plugging in the numbers you get

(21^2 -0)/100 =( 4.4 m/s^2)

Hope this helps :)