Question

When a salmon swims up a river to breed, it often has to jump up waterfalls. The figure shows a salmon jumping above the surface of the water. On this occasion the salmon falls back down into the river.


The salmon has a mass of 2.0 kg.

The salmon leaves the water vertically with a kinetic energy of 16.2 J.


(a) Calculate the speed of the salmon as it leaves the water.





speed = ..............................................


(b) Calculate the maximum height gained by the salmon. Ignore air resistance.





gain in height = ..............................................


(c) Another salmon, of much greater mass, leaves the water vertically with the same speed.

State and explain how the height of this salmon’s jump compares to the height reached by the first salmon.

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Answer 1

Explanation:

kinetic energy = potential energy

1/2mv^2 = mgh

16 .2 = 2*9.8*h

h = 0.826 m

v^2 - u^2 = 2gs

v^2 = 2gh (u is 0 since it's at rest initially)

v = √2*9.8*0.826

= √16

v = 4m/s

if another salmon of much higher weight attempts the same jump , it will still have same maximum

same maximumheight because as you can see , the maximum velocity is based only on initial velocity , and acceleration due to gravity and not mass , therefore it will have same height

happy learning

and please do mark brainliest if you have understood

Answer 2

Answer:

a) K.E = 16.2 J ; m = 2.0 kg

K.E = $\frac{1}{2}mv^2$

16.2 = $\frac{1}{2}$ x 2.0 x $v^2$

16.2 = $1v^2$

$v^2 = 16.2\\v = \sqrt{16.2} \\v = 4.024922359..\\v = 4.02\ m/s$

- Note that 3 significant figures are required.

b) Write out your statement: K.E lost = G.P.E gained

$\frac{1}{2} mv^2$ = mg∆h

16.2 = 2.0 x 9.8 x h

16.2 = 19.6h

h = $\frac{16.2}{19.6}$

h = 0.8265306122..

gain in height = 0.827 m

- Note that gravitational field strength = 9.8 N/kg

c) The salmon will rise to the same height. This is because mass affects both KE and GPE (in the same way).