SV650.org - SV650 & Gladius 650 Forum - Time to redeem yourselves (maffs)

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Time to redeem yourselves (maffs)

Re: Time to redeem yourselves (maffs)

20/20

I iz good maffs to ;)

Re: Time to redeem yourselves (maffs)

19/20, didn;t get the last no. squared -1.

Re: Time to redeem yourselves (maffs)

no comment i was totally rubbish

Re: Time to redeem yourselves (maffs)

Quote:

A tennis ball rolls 40 metres in 26 seconds. If it is rolled with twice the force, how long will it take to roll 80m?

ahem...

if it's rolled with twice the force it will accelerate twice as fast (assuming it's not approaching the speed of light where relativistic equations should be used)

as we dont know the speed at which it starts i will assume it is stationary...

the tennis ball rolls 40m in 20 seconds, therefore it's rate of acceleration is calculated using the equation of motion:

s = ut + 1/2 (at^2)

40 = 0*26 + 0.5 * (a * 26^2)

therefore a = 80 / 676 = 0.1183m/s^2

the acceleration of the ball is proportional to the force applied, therefore if the ball is rolled with twice the force the rate of acceleration will be 0.2367m/s^2

put that back into the equation and you have:

t = sqrt[2s/a] = sqrt[(2*80 / 0.2367)] = 26 seconds

somehow i don;t think that's how they intended you to calculate it though, i think they meant "if the ball is rolled at twice the speed" :D

Re: Time to redeem yourselves (maffs)

Argh, 18/20, I forgot to add "squared" after doing the maths of the rectangle one!

Re: Time to redeem yourselves (maffs)

Quote:

Originally Posted by the_lone_wolf (Post 1557380)

All that time it took you to type that out and nobody will read past the first two lines.

Bravo.

Re: Time to redeem yourselves (maffs)

20/20 8)

Number sequence took me a while though.

Re: Time to redeem yourselves (maffs)

Quote:

Originally Posted by Davido (Post 1557421)

Quote:

Originally Posted by the_lone_wolf (Post 1557380)

ahem...

if it's rolled with twice the force it will accelerate twice as fast (assuming it's not approaching the speed of light where relativistic equations should be used)

as we dont know the speed at which it starts i will assume it is stationary and Davido is a tw*t...

the tennis ball rolls 40m in 20 seconds, therefore it's rate of acceleration is calculated using the equation of motion:

s = ut + 1/2 (at^2)

40 = 0*26 + 0.5 * (a * 26^2)

therefore a = 80 / 676 = 0.1183m/s^2

the acceleration of the ball is proportional to the force applied, therefore if the ball is rolled with twice the force the rate of acceleration will be 0.2367m/s^2

put that back into the equation and you have:

t = sqrt[2s/a] = sqrt[(2*80 / 0.2367)] = 26 seconds

somehow i don;t think that's how they intended you to calculate it though, i think they meant "if the ball is rolled at twice the speed" :D

All that time it took you to type that out and nobody will read past the first two lines.

Bravo.

probably true...

;)

Re: Time to redeem yourselves (maffs)

95% - messed up on the number sequence, so happy to have realised it was the square of the previous number that I forgot the -1 bit Dooh!

I missed the force/speed error and made the same mistake as they did. Good spot from lone wolf and a nice explanation as well!