# Mechanics help?

##### 1 Answer

i)Firstly you should sketch velocity time graph for this question with considering maximum velocity

As acceleration=gradient in velocity time graph

Or you can say

Acceleration=rise/run

Thus you can find velocity easily that will be

So

And as they have asked you to find distance and in velocity time graph

Find area under the graph look at you rough sketch it will be the trapezim area

height is the velocity you found above as

So you distance is

ii)

(ii) Let the car comes to rest after seconds at B. (Assume)

And assume A is point (0,0) on graph

Total distance travelled by car=area of trapezium

The motor cycle starts 20s later

Thus,

total time taken by car from AtoB=

That is

Total distance travelled by motorcycle=area of trapezim

That is

maximum speed reached by motorcycle is, V 37.5 ms

motorcycle travels at constant speed for 30 seconds, therefore total time taken for acceleration and deceleration=20 seconds.

Let time taken for acceleration is t seconds, time taken for deceleration is (20-t)seconds given that., acceleration=3*deceleration

Acceleration

a=

For iii) displacement time graph would be like this I am writing coordinates you can make it