The speedometer of a uniformly accelerating car is read as it crosses each of three equally spaced lines. The reading is 30km/h at the first, 40km/h at the second. What is it at the third?
I tried to turn this into an equation but didn't know how. Would you use V2^2 = V1^2 + 2ad to find d first and then find the velocity? But you don't know exact acceleration! Any help?
On the increment, you know acceleration:
vf^2=vi^2 + 2ad
a= (vf^2-vi^2)/2d= (1600-900)/2d=350/d
so the next final velocity will be...
vf^2=40^2 + 2(350/d)d and you can find that.