is my answer correct..?

Question

If a car has a final velocity of 30 m/s after accelerating for 5.0 seconds at a rate of 5.0 m/s, what is the car's initial velocity?? how far does it travel during this time period??

in question # 1 my answer is 0 "initial velocity"

in question #2 my answer is 75 m

just answer yes or no...but if my answer is not correct..please tell me the correct answer..
:)

Answer 1

no, the answer isnt correct.
don worry, see the answer below-

final velocity, v = 30m/s
Let initial velocity be u m/s
time taken in reaching v from u = t = 5 sec.
acceleration, a = 5m/s*2
applying the first equation of motion, according to which-
v = u + at
substitute the values of v, a and t.
=>30 = u + (5 x 5)
=> u = 5m/s.
so, the initial veocity comes out to be 5 m/s.

question 2 can be solved using 2nd or 3rd equation of motion,
first giving answer thru 2nd equation,according to which-
s= ut + 1/2 at*2
=> s = 5x5 + 1/2 5(5)*2
=> s = 87.5 m
alternatively, it can be solved by third equation of motion-
according to which-
v*2 = u*2 + 2as
substitute all the values,
=> (30)*2 = (5)*2 + 2(5)s
=> 900 - 25 = 10s
=> 875 = 10s
=> s = 87.5 m
hey, that was easy, wasnt it?
:)

Answer 2

The initial velocity is 5 m/s, not 0. If he accelerated at 5 m/s for 5 seconds from ZERO, he would be doing 25 m/s at the end of 5 seconds.

The formula for distance is v0t+.5at^2, = 5*5 + .5*5*5^2 = 25 + 25/2 or 25+125/2, which is not 75, but something more like 87.5

Answer 3

NO!

For the first question use the First equation of Kinematics:

v = u + a*t

u = 30-5*5 = 5 m/s

in question # 1 my answer is 5m/s "initial velocity"
__________ __________ ___________ __________ _________

For the second question use the Second equation of Kinematics:

s = u*t + ½*a*t²

s = 5*5 + ½*5*5² = 25 + 62.5 = 87.5 m

in question #2 my answer is 87.5 m

Answer 4

You have to stop letting Paris teach you Math !..She is to busy with her little dog ( "That's Hot " )..L.O.Laughs!

Answer 5

no