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4 years ago

What would increase the resistance of a copper wire?

1 answer:

3 0

R = ρl/A

From the equation above R = Resistance, l = length, A = Cross Sectional Area of wire.

From the equation, it can be seen that R would increase if the wire's area is reduced.

If the area of the wire is reduced, means the same thing as:

<span>A. decreasing the wire’s thickness</span>

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A steel ball with mass m is suspended from the ceiling at the bottom end of a light, 17.0-m-long rope. The ball swings back and

iogann1982 [59]

Answer:

1. 18.25 m/s

2. 0 m/s

Explanation:

1.So the centripetal acceleration of the ball at this lowest point must be, taking gravity into account

$a_c = \frac{T - mg}{m} = \frac{3mg - mg}{m} = 2g$

The speed at this point would then be

$v^2 = a_c r = 2gr = 2*9.8*17 = 333.2$

$v = \sqrt{333.2} = 18.25 m/s$

2. Similarly, if T = mg, then the centripetal acceleration must be

$a_c = \frac{T - mg}{m} = \frac{mg - mg}{m} = 0$

As the ball has no centripetal acceleration, its speed must also be 0 as well.

6 0

4 years ago

The titanium shell of an SR-71 airplane would expand when flying at a speed exceeding 3 times the speed of sound. If the skin of

Fed [463]

Answer:

The 10-meter long rod of an SR-71 airplane expands 0.02 meters (2 centimeters) when plane flies at 3 times the speed of sound.

Explanation:

From Physics we get that expansion of the rod portion is found by this formula:

$\Delta l = \alpha\cdot l_{o}\cdot (T_{f}-T_{o})$ (Eq. 1)

Where:

$\Delta l$ - Expansion of the rod portion, measured in meters.

$\alpha$ - Linear coefficient of expansion for titanium, measured in $\frac{1}{^{\circ}C}$ .

$l_{o}$ - Initial length of the rod portion, measured in meters.

$T_{o}$ - Initial temperature of the rod portion, measured in Celsius.

$T_{f}$ - Final temperature of the rod portion, measured in Celsius.

If we know that $\alpha = 5\times 10^{-6}\,\frac{1}{^{\circ}C}$ , $l_{o} = 10\,m$ , $T_{o} = 0\,^{\circ}C$ and $T_{f} = 400\,^{\circ}C$ , the expansion experimented by the rod portion is:

$\Delta l = \left(5\times 10^{-6}\,\frac{1}{^{\circ}C} \right)\cdot (10\,m)\cdot (400\,^{\circ}C-0\,^{\circ}C)$

$\Delta l = 0.02\,m$

The 10-meter long rod of an SR-71 airplane expands 0.02 meters (2 centimeters) when plane flies at 3 times the speed of sound.

4 0

3 years ago

Glass absorbs ultraviolet (UV) rays from the Sun. Would a fraction of the incident UV light be reflected from the air/glass boun

fiasKO [112]

Answer:

Yes

Explanation:

Any transparent surface in practical is neither a perfect absorber of electromagnetic waves neither a perfect reflector. Generally all the transparent surfaces reflect some amount of irradiation and the other parts are absorbed and transmitted.

<u>That is given by as relation:</u>

$\alpha+\rho+\tau=1$

where:

$\alpha=$ absorptivity which is defined as the ratio of the absorbed radiation to the total irradiation

$\rho=$ reflectivity is defined as the ratio of reflected radiation to the total irradiation

$\tau=$ transmittivity is defined as the ratio of total transmitted radiation to the total irradiation

6 0

4 years ago

Why are hurricanes considered more damaging than tornadoes when tornadoes have stronger winds

chubhunter [2.5K]

-- A tornado follows a path that's a few miles wide, for a few hours.
   Then it's all over.

-- A hurricane follows a path that's several hundred miles wide,
   for a week or two, before it's over.
   Then comes the rain, continuing on the same path, for another week.

8 0

3 years ago

Read 2 more answers

23. Lunar Gravity Compare the force holding a

romanna [79]

Explanation:

Given

mass of the rock is 10 kg

Force requires to hold the rock is equal to its weight

Weight is given by the product of mass and acceleration due to gravity

Weight on the earth surface

$\Rightarrow W_e=10\times 9.8\\\Rightarrow W_e=98\ N$