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3 years ago

A 4 kg bird has 18 joules of kinetic energy and is rolling 3 m/s. find the mass ?

Physics

1 answer:

vovangra [49]3 years ago

3 0

KE = half of mass times squared speed
18 = 0.5 * mass * (3m/s)^2
18 = 4.5 mass
mass = 18 / 4.5 = 4 kg

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Answer:

955.5N

Explanation:

The normal force is given by the difference between the centripetal force and gravity at the top of the loop:

$F_N = F_C - F_G = m\frac{v^{2} }{r} - mg$

mass m = 65kg

radius of the loop r = 4m

velocity v = ?

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To find the centripetal force, you need to find the velocity of the car at the top of the loop.

Use energy conservation:

$E_{tot}=mgh + \frac{1}{2} mv^{2}$

At the top of the hill:

$E_{tot}= mgh_{hill}$

At the top of the loop:

$E_{tot}=mgh_{loo}_p +\frac{1}{2} m v^{2}$

Setting both energies equal and canceling the mass m gives:

$gh_{hill} = gh_{loo}_p + \frac{1}{2} v^{2}$

Solving for v:

$v^{2} = 2g(h_{hill}-h_{loo}_p)$

Using v in the first equation:

$F_N = \frac{2mg(h_{hill}-h_{loo}_p)}{r} - mg$

$F_N = 955.5N$

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3 years ago

Is it possible that a speed of 254 and a speed of 100 could be the same speed?

EastWind [94]

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However, if the 254 is 'centimeters per time' and the 100 is 'inches per time',
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Всяко действие има равно по големина и противоположно по посока противодействие.

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Answer:

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$t^2=\frac{2\times 1800}{9.8}$

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