2 years ago

Which of these is not an example of a physical change?

Physics

2 answers:

horsena [70]2 years ago

5 0

A. a nail rusting is not a physical change its a chemical change

amm18122 years ago

3 0

A nail rusting is an example of chemical change as the iron is oxidized to become rust. This is not a physical change.

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daser333 [38]

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c) 6.67 W

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(a) the force would generate a torque of:

$T = FR = 18 * 2.4 = 43.2 Nm$

According to Newton 2nd law, the angular acceleration would be

$\alpha = \frac{T}{I} = \frac{43.2}{2100} = 0.021 rad/s^2$

It starts from rest, then after 15s it would achieve a speed of

$\omega = \alpha t = 0.021 * 15 = 0.31 rad/s$

(b) The distance angle swept by it is:

$\theta = \frac{\alpha t^2}{2} = \frac{0.021 * 15^2}{2} = 2.314 rad$

Hence the work by the child

$W = T\theta = 43.2 *2.314 \approx 100 J$

c) Average power to work per time unit

$P = \frac{W}{t} = \frac{100}{15} = 6.67 W$

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