Calculating Time to Catch Up Using Acceleration and Velocity Graphs

[fannyzhou]

ok, the question is like this, you are in a car stopped at a red light. the light goes green adn a car passes you by going 11.om/s E. if you accelerate at 4.0m/s^2 to a maximum speed of 15m/s. How long will it take for you to catch up.
so i know the distance between them is the same.
i tried to use V*T=1/2*A*T^2 but since the t is squared i don' know what to do with it. can anyone help ?thx

 

[fannyzhou]

help please ...

 

[Dorothy Weglend]

ok, the question is like this, you are in a car stopped at a red light. the light goes green adn a car passes you by going 11.om/s E. if you accelerate at 4.0m/s^2 to a maximum speed of 15m/s. How long will it take for you to catch up.
so i know the distance between them is the same.
i tried to use V*T=1/2*A*T^2 but since the t is squared i don' know what to do with it. can anyone help ?thx

Ask yourself this: How long will it take for the stopped car to accelerate to 15 m/s, and how far apart are the cars at that point?

 

[gunblaze]

So.. As you said, since distance is the same, well, you can simply draw out a velocity time graph of both graphs on both diagrams and try working them out right? Its always wiser spending some time drawing the graphs.. Basically, after drawing the graph and working out the equations, you should not be getting a t^2 anymore.