(adsbygoogle = window.adsbygoogle || []).push({}); [SOLVED] M1 level help

Hi.

Could someone please help me with the following M1 level question? I would really appreciate any help as I am really stuck at the moment.

A car starts from rest at a point S on a straight racetrack. The car moves with constant acceleration for 20 s, reaching a speed of 25 m/s. The car then travels at a constant speed of 25 m/a for 120 s. Finally it moves with constant deceleration, coming to rest at a point F.

(a) Sketch a speed-time graph to illustrate the motion of the car.

I did this part.

The distance between S and F is 4 km.

(b) Calculate the total time the car takes to travel from S to F.

I wrote down:

4000 = (0.5 x 20 x 25) + 0.5(120 + (F - 20))x25 and this leads to 50F = 2500.

However, I am not sure if this is correct, or what to do next.

The correct answer is 200 seconds.

Thank you.

Cathy

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: M1 level help

**Physics Forums | Science Articles, Homework Help, Discussion**