Calculating truck speed in collision with a tree | Physics problem solution

[Steveku]

Question:
The driver of a truck slams on the brakes when he sees a tree blocking the road. The truck slows down uniformly with an acceleration of -5.60 m/s2 for 4.20 s, making skid marks 62.4 m long that end at the tree. With what speed does the truck then strike the tree?

Conclusion:
equation: dx = vot + .5at^2
62.4 m = v (4.20s) + .5 (-5.60 m/s^2) (4.20s)
v=26.6 m/s

May you experts please check if this is correct? Thanks a bunch.

 

[malawi_glenn]

is vot the initial velocity*time ?

if so is the case, you only calculated the initial speed of the truck.

v=vo + at

 

[m2003]

I can confirm that your solution is correct. You have correctly used the equation for displacement (dx = vot + .5at^2) and solved for the final velocity (v) using the given values. Your answer of 26.6 m/s is the speed at which the truck strikes the tree. It is important to note that the negative sign on the acceleration indicates that the truck is slowing down, which is consistent with the problem description. Great job!