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# M1 - speed/time watch

1. How would you work out this question?

A particle moves along a straight line. The particle accelerates from rest to a speed of 10 ms-1 in 5s. The particle then moves at a constant speed of 10ms-1 for a period of time. The particle then decelerates uniformly to rest. The period of time for which the particle is travelling at a constant speed is 4 times the period for which it is decelerating.

Find the total time for which the particle is moving.

Any help?
2. (Original post by Mist786)
How would you work out this question?

A particle moves along a straight line. The particle accelerates from rest to a speed of 10 ms-1 in 5s. The particle then moves at a constant speed of 10ms-1 for a period of time. The particle then decelerates uniformly to rest. The period of time for which the particle is travelling at a constant speed is 4 times the period for which it is decelerating.

Find the total time for which the particle is moving.

Any help?
Is that the question exactly as you've got it? Because as it stands, there is no single time answer.
3. (Original post by ghostwalker)
Is that the question exactly as you've got it? Because as it stands, there is no single time answer.
Yes, that's the exact question, except I forgot to write a) Sketch a speed-time graph to illustrate the motion on the particle. (Already sketched it)

Oh, and the total distance travelled by the particle that is given is 480m.
4. (Original post by Mist786)
Oh, and the total distance travelled by the particle that is given is 480m.
That's the bit we need.

So you've sketched the graph, and we have two unknown quantities; how long it's travelling at a constant speed, and how long it takes to decelerate.

We know they are related, so if we call the length of time it decelerates "x", then you can work out what the other time is in terms of x.

You should then be able to set up an equation for the total distance (which you know), and involving working out the area under the graph (which will include x), and solve it.

Once you have x, you should then be able to work out the total time.

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