physic- constant acceleration?

Question

(a) What constant acceleration, in SI units, must a car have to go from zero to 56 mph in 9 s?

(b) What fraction of g is this?

(c) How far has the car traveled when it reaches 56 mph? Give your answer both in SI units and in feet.

Jovan · Accepted Answer

Sorry, I only know the metrics system, but I am sure you'll convert well. 56mph=89.6km/h=24.88 m/s

so the acceleration is 24.88/9=2.76m/s^2
g=9.8m/s^2, so it represents 0.28 g

the distance travelled is 1/2 * 2.76 * 9^2 = 112m

and 112m makes around 367.36 feet...

nocarbs · Answer

a)   v=  u+at

56=  0+ a*9/60*60

a=  56*60*60/  9=  56*3600/9=22400  m/h^2

c)    v^2= u^2+2as

  56^2    = 0+  2*22400*s

s=   56^2/   2*22400=   7/100   miles

physic- constant acceleration?

2 Answers