# Some questions on kinematics.

#### davie08

theres quite a bit of work to do here so just do 1 or 2 if you want and this is the back end of the assignment so these are the harder ones.

1. Homework Statement
1.) an object starts at a velocity of 3.0m/s and accelerates at 4.0m/s^2. Find:
a)the velocity at 2.0s
b)how far it traveled in the first 4.0 s.
c)how far it traveled in the third second.
d)the time it will take to travel 90.0m.

2.)An object starts at rest and accelerates constantly so it moves 22.0m in the sixth second. Find the acceleration.

3.)A car initially traveling at an unknown velocity ends up doubling its velocity in 6,0s while traveling 225.0m. Find:
a)the initial velocity.
b)the acceleration at 3.0 s.
c)the time when it was traveling 10.0m/s faster than when it started.

4.) A curling rock is traveling at a constant of 2.25m/s. If a sweeper starts from the same spot the rock started from and was at rest until 2.00s after the rock started and then accelerates at 1.4m/s^2, find.
a) the time(from when the rock started) they were both going the same speed.
b)how far apart they are at 6.0s after the rock started.

3. The Attempt at a Solution [/b]
Im pretty sure that I have the right answers for a through c so here they are:
a)11m/s
b)76m
c)13m
but I have no clue where to start with d

and the last 3 im pretty lost as well.

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#### LowlyPion

Homework Helper
davie, the way it works here is that you are supposed to do the work. If there is something you are stuck on then ask a question to clear it up. But as to doing your problems for you that does no one any good, especially you come exam time.

#### tnutty

for 1_a use the equation V = V_o +at, where a is acceleration, t is time, v_o is the starting velocity.

For the other one, list what you have for that problem, ex, i have starting velocity, time,and acceleration.Then write what you want to find. Then look at the kinematic equation and see which equation has equation has the thing you want to find, and solve for it if the other variables are given. If not then use another kinematic equation to find that variable and plug it into the original one.

Then if you are really stuck , post it here.

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