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# Kinetic energy and speed

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For this question I have used the kinetic equation to work out 1/2*58*4=116

please show me how to do B, thanks

Mar 11, 2019

#1
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Total energy (TE) = Kinetic energy (KE) + Potential energy (PE)

KE = (1/2).m.v2, where m is mass and v is velocity

PE = m.g.h, where g is gravitational acceleration and h is height (above pool surface).

Calculate TE at diving platform (you have already calculated the KE there).

Work out the PE at the point 6metres below the platform.

Then, because TE is conserved, you can set (1/2)mv2 + PEat6metresbelowplatform= TE, where v is now the velocity at 6m below the platform. This v is the only unknown, so you can rearrange the equation to find it.

Incidentally, you should really give your results with units: Joules for energy, metres/sec for velocity.

Mar 11, 2019

#1
+28357
+4

Total energy (TE) = Kinetic energy (KE) + Potential energy (PE)

KE = (1/2).m.v2, where m is mass and v is velocity

PE = m.g.h, where g is gravitational acceleration and h is height (above pool surface).

Calculate TE at diving platform (you have already calculated the KE there).

Work out the PE at the point 6metres below the platform.

Then, because TE is conserved, you can set (1/2)mv2 + PEat6metresbelowplatform= TE, where v is now the velocity at 6m below the platform. This v is the only unknown, so you can rearrange the equation to find it.

Incidentally, you should really give your results with units: Joules for energy, metres/sec for velocity.

Alan Mar 11, 2019
#2
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ok...

so TE = 116 + (58*9.81*6) = 5921.8

my gpe under 6M: .(58*9.81*6)= 3529.88

5805.8 - 3529.88 = 2275.92

2507.2 = 1/2 58v^2

86.48= v^2

v= 9.3 ms^-1

YEEEEEET  Mar 11, 2019
#3
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thank you so much for teaching me

YEEEEEET  Mar 11, 2019