Homework Help: physics

Posted by Katy on Wednesday, January 19, 2011 at 11:12am.

A train is moving parallel and adjacent to a
highway with a constant speed of 22 m/s. Initially a car is 69 m behind the train, traveling
in the same direction as the train at 35 m/s
and accelerating at 3 m/s
2
.
What is the speed of the car just as it passes
the train

physics - Henry, Thursday, January 20, 2011 at 8:56pm
D1 = D2 - 69.
V*t = Vo + 0.5at^2 -69,
22t = 35t + 0.5 * 3t^2 - 69,
22t = 35t + 1.5t^2 - 69,
22t - 1.5t^2 - 35t = -69,
-1.5t^2 -13t + 69 = 0,
Multiply both sides by -1:
1.5t^2 + 13t - 69 = 0.
Using Quadratic Formula,

t = (-13 +- sqrt(169 + 414)) / 3,
t = (-13 +- 24.1) / 3,
t = 3.72, and -12.37.
Use the positive value of t:
t = 3.72s.

V = Vo + at = 35 + 3 * 3.72 = 46.12m/s.

Answer this Question

Related Questions

physics - A train is moving parallel and adjacent to a highway with a constant ...
Physics - A train is moving parallel and adjacent to a highway with a constant ...
physics - A train is moving parallel and adjacent to a highway with a constant ...
physics - A train is moving parallel to a highway with a constant speed of 16.0 ...
physics - Cora is a passenger in a car traveling east along a country highway ...
Engineering Physics - A car and a train move together along straight, parallel ...
physics - The last car unfastens from a moving train. The train continues to ...
Physics - You are conducting an experiment inside a train car that may move ...
Physics - You are conducting an experiment inside a train car that may move ...
Physics - You are conducting an experiment inside a train car that may move ...

For Further Reading

First Name:
School Subject:
Answer: