• Mar 20th 2007, 06:51 PM
qbkr21
If a ball is given a push so that it has an initial velocity of 5 m/s down a certain inclined plane, then the distance it rolled arter t seconds is s = 5t + 3t^2.

a) Find the velocity after 2 seconds?
v(t) = 5 + 6t
v(2) = 5 + 6(2)
V(2) = 17

b) How long does it take for the velocity to reach 35 m/s?

35 = 5 + 6t
-5 -5
30 = 6t
so I divided 30/6 = 6t/6

5 seconds

Am I right?
• Mar 20th 2007, 07:04 PM
Jhevon
Quote:

Originally Posted by qbkr21
If a ball is given a push so that it has an initial velocity of 5 ms/s down a certain inclined plane, then the distance it rolled arter t seconds is s = 5t + 3t^2.

a) Find the velocity after 2 seconds?
v(t)= 5 + 6t

You didn't complete this. plug in 2 for t and you've got the answer.

Quote:

b) How long does it take for the velocity to reach 35 m/s?

35 = 5 + 6t
-5 -5
30 = 6t
so I divided 30/6 = 6t/6

5 m/s
Am I right?
this is right, except the units. it's 5 seconds, not 5 m/s. m/s is velocity, they asked for time