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2 years ago

Can someone please help thank u (. ^ ᴗ ^. )

Physics

2 answers:

Mila [183]2 years ago

8 0

Answer:

3) The answer is (b) -8 m/s (pointing down)

4) The answer is (c) -9.8 m/s^2 (acceleration of a freely falling object is always due to gravity, -9.8 m/s^2, regardless o

Explanation:

kakasveta [241]2 years ago

6 0

3) The answer is (b) -8 m/s (pointing down)

4) The answer is (c) -9.8 m/s^2 (acceleration of a freely falling object is always due to gravity, -9.8 m/s^2, regardless of direction)

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A copper cable needs to carry a current of 160 A with a power loss of only 2.0 W/m. What is the required radius of the copper ca

lesantik [10]

Answer:

The radius of the cable is 0.0083 m or 8.3 mm.

Explanation:

The resistance of copper cable of 1 meter length will be given by

$R_{cable} = \frac{\rho \times l}{a}$ .... (i)

where the resistivity of copper is $\rho = 1.7 \times 10^{-8} \Omega.m$ , and l is the length of the wire which is considered to be 1m, and a is the cross sectional area of the wire in $m^{2}$ .

From the formula of power we know that, $P = I^2 R$ .... (ii)

Therefore 2 W/m = $(160)^2 \times R$ .... (iii)

where the resistance,R, actually means the resistance of the cable per meter.

Therefore R ( resistance of cable per meter)

= $\frac{2}{160^2} = 7.812 \times 10^{-5}$ ohms / meter. .... (iv)

Therefore from (i)

$7.812 \times 10^{-5}$ = $\frac{1.7 \times 10^{-8} \times 1}{a} = \frac{1.7 \times 10^{-8} \times 1}{\pi r^{2} }$ ..... (v)

where cross sectional area of the cable, a = $\pi r^2$ ,

where r is the radius of the cable, and length of cable,l = 1m.

Therefore r = $\sqrt{\frac{ 1.7 \times 10^{-8}}{\pi \times 7.812 \times 10^{-5} } } = 0.0083m = 8.3 mm$

5 0

3 years ago

A group of animals have short, narrow legs that are partly webbed. In which environment do these animals MOST LIKELY live? A) de

Burka [1]

I'd say it's answer D) rainforests

7 0

2 years ago

Read 2 more answers

if a runners power is 400 watts as she runs, how much chemical energy does she convert into other forms in 10 minutes

AnnZ [28]

Answer:

Energy converted = $240000\,Joules = 240\, kJoules$

Explanation:

Recall that Power is the rate at which energy is transferred therefore defined by the mathematical formula: $Power\,=\,\frac{Energy\,transferred}{time}$

Since the information on the power of the runner is given, as well as the time the energy conversion takes place, we can then use this equation to find how much energy is been converted. Notice that we just need to change the given time *10 minutes) into the appropriate units (seconds)to get the answer in SI units of energy (Joules). The conversion of 10 minutes into seconds is done by multiplying : 10 minutes * 60 seconds/minute = 600 seconds.

We use this then to find the energy converted by the runner:

$Power\,=\,\frac{Energy\,transferred}{time}\\400 \,W = \frac{E}{600\,sec} \\400 \,W * 600\,sec=E\\E=240000\,Joules = 240\, kJoules$