Question

Can someone check my work on this?

A truck carrying a 38 kg crate accelerates uniformly from rest to 87.5 km/hr (<-- which I converted to 24.31 m/s) in 12.1 s. Calculate the work done on the crate by the truck.

force = (38)(9.8) = 372.4
distance = 24.31*21 = 510.51
force * distance = 190113.9 = work
(What units would this be?)

Answer 1

Force = m x a
where m is mass of truck, and a is acceleration of truck

a = (vt -vo)/t
where vt is the final speed, vo is the initial speed, and t is time.,
a = (24.31 m/s - 0)/ 12.1 s
a = 2 m/s^2

So
Force = m x a
Force = 38 kg x 2 m/s^2
Force = 76 N

Finally

Work = F x s
Work = 76 N x (vo t + 1/2 at^2) m
Work = 76 N x (0+ (0.5 x 2 x 12.1^2)) m
Work = 76 N x 146.41 m
Work = 11127.16 Joule

Answer 2

@sponkers_w ???

Answer 3

ohhhhh okay. I guess I need to practice the acceleration bit more.

Answer 4

@sponkers_w check this out

http://www.physicsclassroom.com/Class/1DKin/U1L1e.cfm

maybe thats useful

Answer 5

@sponkers_w you forgot to give me a medal :)