Not the regular old kinematic question- help

[bingo92]

Homework Statement

A car accelerates uniformly from an initial velocity for 6s. The displacements in the 3rd and the 5th seconds are 12m and 18m respectively. Find the acceleration and the initial velocity of the car.

(Answer: 3m/s^2 , 4.5 m/s)

Btw this from a first year physics course for science majors...

Homework Equations

same -kinematics equations

The Attempt at a Solution

 

[ideasrule]

You are given time and displacement; you need to find acceleration and initial velocity. Which equation relates all four variables?

 

[Fewmet]

ideasrule: I wrestled with the wording for a long time, thinking it meant that the car was at d=12 m at t=3 s and at d=18 m at t=5 s. Is that being an obstacle for you, too?

 

[gneill]

The first second spans t=0 to t=1, the second second spans t=1 to t=2, the third second spans t=2 to t=3, and so on.

 

[Fewmet]

ideasrule: I wrestled with the wording for a long time, thinking it meant that the car was at d=12 m at t=3 s and at d=18 m at t=5 s. Is that being an obstacle for you, too?

Sorry: I should have directed that comment to bingo92, not ideasrule.

Gneill: Thanks. The thing that made me waste time was not seeing that it moved 12 m between t=2 s and t=3 s. Once I got that cleared up, the answer a=3m/s² followed quickly.

 

[Redbelly98]

Homework Statement

A car accelerates uniformly from an initial velocity for 6s. The displacements in the 3rd and the 5th seconds are 12m and 18m respectively. Find the acceleration and the initial velocity of the car.

Welcome to Physics Forums.

Okay, so what is:

• The average velocity during the 3rd second?
• The average velocity during the 5th second?