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Svetlanka [38]
3 years ago
7

3. A train covers 168 km in 4 hours. How much distance will it cover in 80 minutes?

Physics
1 answer:
Kay [80]3 years ago
4 0

Answer:

56km

Explanation:

168 ÷ 240 = 0.7

0.7 × 80 = 56km

240 is the amount of minutes in 4 hours.

We divided 168 by 240 to get the distance covered in 1 minute. Afterwards, we needed 80 minutes so we multiplied the answer by 80.

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How does the period affects the centripetal force?
Anna71 [15]

Answer:According to the Equation (2), centripetal force is proportional to the square of the speed for an object of given mass M rotating in a given radius R.

Explanation:The Period T. The time T required for one complete revolution is called the period. For. constant speed. v = 2π r T holds.

8 0
3 years ago
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A bike travels 4 miles in half an hour, what is its speed?
omeli [17]

Answer:

8 mph

Explanation:

4 miles in half hour so you add 4 more for the second half

3 0
3 years ago
What is the first semiconductor
madam [21]
<span>
English "natural philosopher" (the contemporary term for physicist) Michael Faraday is renowned for his discovery of the principles of electro-magnetic induction and electro-magnetic rotation, the interaction between electricity and magnetism that led to the development of the electric motor and generator. The unit of measurement of electrical capacitance - the farad (F) - is named in his honor. Faraday's experimental work in chemistry, which included the discovery of benzene, also led him to the first documented observation of a material that we now call a semiconductor. While investigating the effect of temperature on "sulphurette of silver" (silver sulfide) in 1833 he found that electrical conductivity increased with increasing temperature. This effect, typical of semiconductors, is the opposite of that measured in metals such as copper, where conductivity decreases as temperature is increased. In a chapter entitled "On Conducting Power Generally" in his book Experimental Researches in Electricity Faraday writes "I have lately met with an extraordinary case ... which is in direct contrast with the influence of heat upon metallic bodies ... On applying a lamp ... the conducting power rose rapidly with the heat ... On removing the lamp and allowing the heat to fall, the effects were reversed." We now understand that raising the temperature of most semiconductors increases the density of charge carriers inside them and hence their conductivity. This effect is used to make thermistors - special resistors that exhibit a decrease in electrical resistance (or an increase in conductivity) with an increase in temperature. <span> Next Milestone </span> Contemporary Documents <span> <span>Faraday, M. Experimental Researches in Electricity, Volume 1. (London: Richard and John Edward Taylor, 1839) pp.122-124 (para. 432). Note: This section appears on different pages in later editions of the book. The material in the book is reprinted from articles by Faraday published in the Philosophical Transactions of the Royal Society of 1831-1838. </span> </span> More Information <span> <span>Hirshfeld, Alan W. The Electric Life of Michael Faraday. Walker & Company (March 7, 2006).</span> <span>Friedel, Robert D. Lines and Waves: Faraday, Maxwell and 150 Years of Electromagnetism. Center for the History of Electrical Engineering, Institute of Electrical and Electronics Engineers (1981).</span> </span> </span>
3 0
4 years ago
A girl playing tug-of-war with her dog pulls the dog a distance of 8.0m by exerting a force at an angle of 18° with the horizont
AnnZ [28]

Answer:

25 N

Explanation:

Work is a product of force and perpendicular distance moved.

W=Fd where F is force exerted and d is perpendicular distance.

However, for this case, the distance is inclined hence resolving it to perpendicular so that it be along x-axis we have distance as dcos\theta

Therefore, W=Fdcos\theta

Making F the subject of the formula then

F=\frac {W}{dcos\theta} where \theta is the angle of inclination. Substituting 190 J for W then 18 degrees for \theta and 8 m for d then

F=\frac {190}{8cos18^{\circ}}\approx 25N

3 0
3 years ago
There is a naturally occurring vertical electric field near the Earth’s surface that points toward the ground. In fair weather c
trasher [3.6K]

Answer:

\frac{F}{W} = 9.37 \times 10^{-4}

Explanation:

Radius of the pollen is given as

r = 12.0 \mu m

Volume of the pollen is given as

V = \frac{4}{3}\pi r^3

V = \frac{4}{3}\pi (12\mu m)^3

V = 7.24 \times 10^{-15} m^3

mass of the pollen is given as

m = \rho V

m = 7.24 \times 10^{-12}

so weight of the pollen is given as

W = mg

W = (7.24 \times 10^{-12})(9.81)

W = 7.1 \times 10^{-11}

Now electric force on the pollen is given

F = qE

F = (-0.700\times 10^{-15})(95)

F = 6.65 \times 10^{-14} N

now ratio of electric force and weight is given as

\frac{F}{W} = \frac{6.65 \times 10^{-14}}{7.1 \times 10^{-11}}

\frac{F}{W} = 9.37 \times 10^{-4}

7 0
3 years ago
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