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3 years ago

A person can run 280 m in 68 s. At what speed are they running?

Physics

2 answers:

ella [17]3 years ago

6 0

Answer:

Explanation:

Hi there,

280 miles in 68 seconds

280/68 in 1 second

= 4.12 miles per second

or 4.12 x 60

247.2 miles per minute

or 247.2 X 60

= 14832 miles per hour

Hope this helps :-)

liq [111]3 years ago

5 0

D = 280m

t = 68 s

S = D/t

=280/68

= 4.1 m/s

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four forces act on an object of mass 100kg, they are 12N(N), 70N(S), 33N(E), 10N(w). calculate the reseulting acceleration of th

trapecia [35]

Answer:

0.62 m/s² at 68° S of E

Explanation:

Net force north = 12 - 70 = -58 N

Net force east = 33 - 10 = 23 N

Net force = √(-58² + 23²) = 62.3939... N

acceleration = F/m = 62.3939/100 = 0.623939... ≈ 0.62 m/s²

θ = arctan(-58/23) = -68.3691... ≈ 68° S of E

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3 years ago

if you place 0°c ice into 0°c water in an insulated container, what will happen? Will some ice melt, will more water freeze, or

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Answer:

neither will happen

Explanation:

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2 years ago

A 190 g rock at 20°C is completely immersed in 600 g of water at 80°C. Which one of the following statements is true right after

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3 years ago

Three charges, Q1, Q2, and Q3 are located in a straight line. The position of Q2 is 0.301 m to the right of Q1. Q3 is located 0.

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Answer and Explanation: A charge exerts a force over another charge even if they are very far apart. This force is called <u>Electrostatic</u> <u>Force</u>.

If the two charges have the same sign, e.g. both aare positive, the force between them is opposite. If they have opposite sign, the force is towards each other. In other words, for electrostatic force, equal charges repel and different charges attract.

So,

1. If Q2 and Q3 have opposite signs, it is TRUE force in Q2 will go the left;

2. If the 2 are negative, they have the same sign, so it's FALSE force is to the right;

Sentences 3 and 4 are also TRUE due to the reasons described above;

5. If the charges have opposite signs, it means force is towards each other, or, to the right, so the sentence is TRUE;

1. Force is directly proportional to charges in Coulomb [C] and inversely proportional to distance squared in [m]:

$F=\frac{k.q.Q}{r^{2}}$

where k is a constant that equals 9 x 10⁹ N.m²/C²

Calculating force between 1 and 2:

$F_{12}=\frac{9.10^{9}(1.9.10^{-6})(2.84.10^{-6})}{(0.301)^{2}}$

$F_{12}=536.02.10^{-3}$ N

Force between 2 and 3:

$F_{23}=\frac{9.10^{9}(2.84.10^{-6})(3.03.10^{-6})}{(0.169)^{2}}$

$F_{23}=2711.63.10^{-3}$ N

Total force is the net force. Since Q2 is negative and the others are positive, force of 2 related to 1 is to left and related to 3 is to the right. Therefore, total force is the difference between those two forces:

$F_{T}=2711.63.10^{-3}-536.02.10^{-3}$

$F_{T}=2175.61.10^{-3}$ N

The total force on Q2 is 2175.61 x 10⁻³ N

2. For net force to be 0, $F_{13}=F_{23}$ . Suppose distance from 1 to 3 is x, then from 2 to 3 is $x-0.301$

Calculating:

$\frac{k(1.90.10^{-6})(3.03.10^{-6})}{x^{2}}=\frac{k(2.84.10^{-6})(3.03.10^{-6})}{(x-0.301)^{2}}$

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$\frac{5.757.10^{-12}}{8.6052.10^{-12}}=\frac{x^{2}}{x^{2}-0.602x+0.090601}$

$x^{2}=0.67x^{2}-0.40x+0.061$

$0.33x^{2}+0.40x-0.061=0$

roots = 0.14 or -1.35

Solving quadratic equation gives 2 roots, but one of the roots is negative. As distance is a measure that cannot be negative, the solution is x = 0.14.

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Answer: False

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