Year 12s: what will be the first way you research your future options? >>

Mechanics

I'm really struggling with mechanics in general and can't do this exercise. I got the first part of 6 correct with 23.83 but then for the second part I did 4=4-(2.75xt) giving t as 3.2 which was wrong so help there please.

For 7 I did 80^2/2x1000 which was 3.2 and correct

For 8 I used v=0+1.5x8=12 then t=v-u/a and got 12 but this is wrong so help please

For 9 I did v=0+(10x0.625)= 6.25 then using s=vt-1/2at^2 so (6.25x10)-1/2x0.625x10^2=31.25 which was wrong

I couldn't do 10 or 11 at all.

Please help me with all of these

Anyone?

For 6ii) you have averaged the acceleration however the time spent in each acceleration phase is different (not 50/50) so you can't do this.

use v=u+at for each acceleration phase separately then add them.

For 8 you need to consider
it going up the slope when accelerating
going up the slope whilst decelerating
going down the slop back to the start.

(edited 7 years ago)