# Calculate speed of the car when t = 6 (mechanics)

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#1
Question (i): http://prntscr.com/uhjjnr

v = u + 0.8t(t) = 13 + 0.8(6)^2 = 41.8 m/s

What did I do wrong?? The ans. is 27.4 m/s.
0
1 month ago
#2
(Original post by TSR360)
Question (i): http://prntscr.com/uhjjnr

v = u + 0.8t(t) = 13 + 0.8(6)^2 = 41.8 m/s

What did I do wrong?? The ans. is 27.4 m/s.
Look, acceleration is 0.8t and not just 0.8. So it depends on time, hence it is not constant, hence SUVAT is not applicable here.

You need to use calculus.
Last edited by RDKGames; 1 month ago
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#3
(Original post by RDKGames)
Look, acceleration is 0.8t and not just 0.8. So it depends on time, hence it is not constant, hence SUVAT is not applicable here.

You need to use calculus.
oh right, i forgot about that. Thanks!
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