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2 years ago

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A child is riding a bike at a speed of 6m/s with a total kinetic energy of 1224J. If the mass of the child is 30kg, what is the

mass of the bike?

1 answer:

UkoKoshka [18]2 years ago

3 0

Answer:

Mass of bike = 38 kg.

Explanation:

Kinetic energy is given by the expression, $KE = \frac{1}{2} mv^2$ , where m is the mass and v is the velocity.

Here speed of child riding bike = 6 m/s

Mass of child = 30 kg

Total kinetic energy = 1224 J

Let the mass of bike be, m kg

So, total mass of child and bike = (m + 30) kg

Substituting,

$1224 = \frac{1}{2}* (m+30)*6^2\\ \\ m+30=68\\ \\ m=38kg$

So, mass of bike = 38 kg.

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If no frictional work is considered, then the energy of the system (the driver at all positions is conserved.

Let
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where g = acceleration due to gravity,
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PE in position 1 is converted into KE due to the loss in height from position 1 to position 2.

Therefore
(KE + PE) ₁ = (KE + PE)₂

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2 years ago

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Answer:

Explanation:

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2 years ago

A student, along with her backpack on the floor next to her, are in an elevator that is accelerating upward with acceleration a.

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Answer:

$\mu_k = \frac{2(vt - L)}{(g + a) t^2}$

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As we know that backpack is kicked on the rough floor with speed "v"

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$N - mg = ma$

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$a = - \frac{F_f}{m}$

$a = -\mu_k(g + a)$

now we know that bag hits the opposite wall at L distance away in time t

so we have

$d = v t + \frac{1}{2}at^2$

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2 years ago

While ice skating, you unintentionally crash into a person. Your mass is 60 kg, and you are traveling east at 8.0 m/s with respe

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Answer:

6.18 m/s

Explanation:

Roller skate collision

The final direction of the system (me=M + person=P) velocity vector is at an angle; Ф, to the direction running south to north. Apply the component form of the impulse-momentum equation, firstly;

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$P_{Miy}$ + $p_{Piy}$ + $j_{y}$ = $P_{Mfy}$ + $P_{pfy}$

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y-axis component form (+y north);

$P_{Mix}$ + $p_{Pix}$ + $j_{x}$ = $P_{Mfx}$ + $P_{pfx}$

$m_{Mu_{Mix}+ m_{pu_{pix}}+0=(m_{M}+m_{p})V_{f} cos$ Ф

0 + 80.9 = (60 + 80) $V_{f}cos$ Ф

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Substituting (2) into (1) to give the angle;

480 = 720tan Ф

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note 1:

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2 years ago

A 74.9 kg person sits at rest on an icy pond holding a 2.44 kg physics book. he throws the physics book west at 8.25 m/s. what i

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Answer:

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$p_{i}$ = $p_{f}$

System initially is at rest

∴ $p_{i}$ =0

∴ From the above 2 equations

$p_{f}$ =0

We know that ,

Momentum(p)=Mass of the body(m)×velocity of the body(v)

Let $m_{1}$ and $m_{2}$ be the mass of the person and the book respectively and $v_{1}$ and $v_{2}$ be the final velocities of the person and book respectively.

∴ $p_{f}$ = $m_{1}$ $v_{1}$ + $m_{2}$ $v_{2}$ =0

From the question ,

$m_{1}$ = 74.9 kg

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Substituting these values in the above equation we get ,

(74.9 × $v_{1}$ )+ (2.44×8.25) = 0

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2 years ago