Vertical motion under gravity - book falling from a shelf : ExamSolutions

Tutorial on vertical motion under gravity.
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[@MultiTbeast]

i think this has been answered below but not too clearly :) how did you get the fraction 784/25 i really cant see it. 9.8 x 2 = 19.6 x 1.6 erm ok i cant do that :) erm you doing 19.6 x 10 = 196, times 1.6 times 10 = 16 ? 196 x 16 = 3136 ? / 10 = 313.6 no ok i really have no idea :) please help :)

[@ExamSolutions_Maths]

Your right. I meant to write 2x98/10 x 16/10

[@leonzspotg]

Oh no

[@MultiTbeast]

IGNORE ME FORGOT WE CAN USE A CALCULATOR AHA xD Your the best ! I will be donating after every exam i take :) as celebration and thanks to you !!!!

[@ExamSolutions_Maths]

Kick it off the shelf if I was you.

[@H2KqLimAxzU16]

Sir should you use values you calculated to calculate other unknown values or instead use the values that the question had already gave,this being in the second case; since I used s=(u+v /2)*t...
Thanks.

[@ExamSolutions_Maths]

You can use either methods. However, if you are able to avoid the ones calculated then obviously if one of the calculated values is used and it was wrong then this will make the following calculation wrong.

[@H2KqLimAxzU16]

Right thanks Sir!

[@lawrencepoon3613]

SORRY SIR
98/100 is not equal to 9.8 and how come /25??
thank you sir for help!!

[@ExamSolutions_Maths]

2x98/100x16/10

[@ExamSolutions_Maths]

Yes

[@leonzspotg]

Yes

[@IGCSETutorials]

Yes

[@anthonychineduifedigbo13]

How is the displacement still positive if its movies downwards

[@ASLUHLUHC3]

He chose to make downwards the positive direction (as specified in his diagram). Even if you make upwards the positive direction, you'd get the same answer for speed (which denotes no direction)

[@ololade_thegreat]

Really enjoyed d projectiles lesson keep d flag flying

[@AA18F]

thank you very much for this, i was gonna kill my mechanics book if i didnt see this

[@sadeel8961]

why didnt u take a to be negative so -9.81

[@hamzahwaheed9528]

Why is s= 1.6 and not -1.6?

[@MoneyyMojo]

downwards is taken as the positive direction ( Shown with a positive acceleration )

[@nabikebabi]

how are you getting 784/25?? explain please

[@danyold6494]

2*9.8*1.6=784/25

[@davidgoodman8469]

how do you get 784/25 i just multiplied 2*9.8*1.6=31.36 then the root of that =5.6. I have no idea where the 784 divided by 25 came from what am I missing?

[@ExamSolutions_Maths]

The calculator I used converted the decimals to exact fractions. 2x(98/10)x(16/10)

[@davidgoodman8469]

ah makes sense ty

[@AA18F]

:D indeed