physical science homework????

Question

please show all work so i can see how u got the answer, thanks :)

1. A train is accelerating at a rate of 2.0 km/hr/sec. If its initial velocity is 20 km/hr, what is its velocity after 30 seconds???

i got 80 km/hr is that correct?

2. A runner achieves a velocity of 11.1 m/s 9 seconds after he begins.
what is his acceleration??

i think the formula is

acceleration= initial velocity - final velocity
--------------------------------
time

Answer 1

First- spot on!
2.0km/hr/sec x 30sec = (30 x 2)= 60km/hr
60km/hr (change in acceleration times time) + 20km/hr (initial velocity) = 80km/hr (final)

Second... not quite.
Acceleration is "Change in Velocity/Time"
So:
A final velocity of 11.1m/s
An initial velocity of 0 m/s (starting speed)
Time between the initial and final velocities is 9 sec

(11.1 - 0) / 9 = 1.233 m/s/s

Remember to use conversion factors to match up the units, if needed.
Velocity = Distance/Time
Acceleration = Velocity/Time

Answer 2

first answer is correct.

second (your formula is wrong, it should be final-initial):

assuming the runner starts from rest

11.1-0 = 11.1

time = 9 s

acceleration = 11.1/9 = 1.23 meters/seconds Squared m/s^2

Answer 3

1. Yes your answer is correct.
2. No, it should be acceleration=final-initial