Question-97629

Question Number 97629 by peter frank last updated on 08/Jun/20

Answered by Rio Michael last updated on 09/Jun/20

mass of man = 100 kg height jumped = 5 m time = 0.4 s Velocity of the dude v = (√(2gh)) = (√(2 × 9.8 ms^(−2) × 5m)) = 9.9 ms^(−1) Force F = ((mΔv)/t) = ((m(v_2 −v_1 ))/t) = ((100 kg(0 −9.9) ms^(−1) )/(0.4 s)) ≈−2500 N the negative indicates that the direction of the force opposes motion. weight of dude = mgh = 100 kg × 9.8 ms^(−2) = 980 N ⇒ Average force = W + F = 2500 N + 980 N = ......

$$\:\mathrm{mass}\:\mathrm{of}\:\mathrm{man}\:=\:\mathrm{100}\:\mathrm{kg} \\ $$$$\mathrm{height}\:\mathrm{jumped}\:=\:\mathrm{5}\:\mathrm{m} \\ $$$$\mathrm{time}\:=\:\mathrm{0}.\mathrm{4}\:\mathrm{s} \\ $$$$\:\mathrm{Velocity}\:\mathrm{of}\:\mathrm{the}\:\mathrm{dude}\:{v}\:=\:\sqrt{\mathrm{2}{gh}}\:=\:\sqrt{\mathrm{2}\:×\:\mathrm{9}.\mathrm{8}\:\mathrm{ms}^{−\mathrm{2}} \:×\:\mathrm{5m}}\:=\:\mathrm{9}.\mathrm{9}\:\mathrm{ms}^{−\mathrm{1}} \\ $$$$\mathrm{Force}\:\mathrm{F}\:=\:\frac{{m}\Delta{v}}{{t}}\:=\:\frac{{m}\left({v}_{\mathrm{2}} −{v}_{\mathrm{1}} \right)}{{t}}\:=\:\frac{\mathrm{100}\:\mathrm{kg}\left(\mathrm{0}\:−\mathrm{9}.\mathrm{9}\right)\:\mathrm{ms}^{−\mathrm{1}} }{\mathrm{0}.\mathrm{4}\:\mathrm{s}}\:\approx−\mathrm{2500}\:\mathrm{N} \\ $$$$\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{negative}}\:\boldsymbol{\mathrm{indicates}}\:\boldsymbol{\mathrm{that}}\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{direction}}\:\boldsymbol{\mathrm{of}}\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{force}}\:\boldsymbol{\mathrm{opposes}}\:\boldsymbol{\mathrm{motion}}. \\ $$$$\mathrm{weight}\:\mathrm{of}\:\mathrm{dude}\:=\:\mathrm{mgh}\:=\:\mathrm{100}\:\mathrm{kg}\:×\:\mathrm{9}.\mathrm{8}\:\mathrm{ms}^{−\mathrm{2}} =\:\mathrm{980}\:\mathrm{N} \\ $$$$\Rightarrow\:\mathrm{Average}\:\mathrm{force}\:=\:\mathrm{W}\:+\:\mathrm{F}\:=\:\mathrm{2500}\:\mathrm{N}\:+\:\mathrm{980}\:\mathrm{N}\:=\:…… \\ $$$$ \\ $$

Commented by Rio Michael last updated on 09/Jun/20

$$\mathrm{thanks}\:\mathrm{Mr}\:\mathrm{W}\:\mathrm{for}\:\mathrm{spoting}\:\mathrm{that} \\ $$

Commented by mr W last updated on 09/Jun/20

$${wrong}. \\ $$$${mgh}\:{is}\:{never}\:{a}\:{force}! \\ $$

Commented by Rio Michael last updated on 09/Jun/20

hahh sorry that should be an error, due excitement of the question. Bro, Weight of the dude = mg = 100 kg ×9.8 ms^(−2) = 980 N

$$\mathrm{hahh}\:\mathrm{sorry}\:\mathrm{that}\:\mathrm{should}\:\mathrm{be}\:\mathrm{an}\:\mathrm{error},\:\mathrm{due}\:\mathrm{excitement} \\ $$$$\mathrm{of}\:\mathrm{the}\:\mathrm{question}. \\ $$$$\mathrm{Bro},\:\mathrm{Weight}\:\mathrm{of}\:\mathrm{the}\:\mathrm{dude}\:=\:\mathrm{mg}\:=\:\mathrm{100}\:\mathrm{kg}\:×\mathrm{9}.\mathrm{8}\:\mathrm{ms}^{−\mathrm{2}} \:=\:\mathrm{980}\:\mathrm{N} \\ $$

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