Physics homework help...?

Question

The head of a rattlesnake can accelerate 50 m/s2 in striking a victim. If a car could do as well, how long would it take to reach a speed of 97 km/h from rest?

-What I did was divide the rate of acceleration by the speed and got 1.9 s. However that is the wrong answer.... What am I doing wrong?

Answer 1

you've not converted the speed from km/h to m/s.

to do that you first multiply by 1000 and then divide by 3600. so the end speed is 26.94m/s (if my maths is right!)

then by using the formula v = u + at you can find the time.

so u = 0  v = 26.94  a = 50  t = ?

26.94 = 0 + 50t

26.94 = 50t

t = 26.94/50

t = 0.5388

so the time is 0.539 seconds.

assuming my calculations are correct.