# can someone solve this physics problems.?

1 The mass of three wires of copper are in the ratio 1:3:5 and their lengths are in the ratio 5::1.Find the ratio of their electrical resistance.

2. A block of mass M is pulled along a horizontal frictionless surface by a rope of mass m if a force is applied at one end of the rope,the force which the rope exerts on the block will be what?

3. A wire has a resistance 30 ohm. it is bent in the form of a regular hexagon ABCDEF and the two ends are joined together . Find the effective resistance between the point A and B.

4. the area of a quadrilateral ABCD whose sides are 9m, 40m, 28m and 15m will be what.

### 5 Answers

- KenKLv 61 decade agoFavourite answer
3) Each leg of the hexagon is the same length, so each leg is 5 ohms. Since the wire is connected, there are 2 paths for current to flow 1) Directly from A to B, and 2) From B to C to D to E to F to A (5 sides). This acts like a 5 ohm resistor in parallel with a 25 ohm resistor. I will let you figure it from here, but I would guess the answer is approximately 4.2? ohms.

#2) Since there is no friction, both objects use force to accelerate based on their mass. The total mass is m + M. The force = mass * acceleration equation is then written as f = (m + M) * a

The force used to accelerate the box is the box's mass in a ration to the total , or M/(m + M).

I hope that helps.

- PearlsawmeLv 71 decade ago
I hope the lengths are in the ratio 5:3:1.

The resistance is directly proportional to the length.

The resistance is inversely proportional to the Area of cross section

R = k * l/A

If m is the mass, then its area of cross section A = m / {l*d} where d is the density and l is its length.

R = k *l^2 d / m.

d is a constant.

R = Kl^2/m

R1:R2:R3 = l1^2/m1:L2^2/m2:l3^2/m3 = 5^2/1: 3^2/3:1^2/5

=25:3:0.2

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2)

If a is the acceleration of the block, and If T is the tension,

the force pulling the block is T = F- ma.

If the block moves with constant velocity then a = 0 and

T = F.

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3)

The resistance of AB is R and that of AFEDCB is 5R.

1/ R (effective) = 1/R + 1/ [5R] = [6/5] *[1/R] = 6/25 since R =5

R effective = 4.17 ohm

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http://mathcentral.uregina.ca/QQ/database/QQ.09.06...

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- 1 decade ago
1. let, masses are m,3m,5m and lengths are 5l, 3l and l.so, ratio of resistances r1:r2:r3=p(5l)/A1 : p(3l)/A2 : p(l)/A3 = 5pl^2/V1 : 3pl^2/V2 : pl^2/V3 = 5/(m/d) : 3/(3m/d) : 1/(5m/d) = 5 : 1 : (1/5)

2. if force at the end of the rope is F, F=(M+m)a

the force exerted on block is T=Ma=MF/(M+m)

3. points A and B are joined parallely by part AB(5 ohm) and AFEDC(5+5+5+5+5=25 ohm). so, if equivalent resistance is R, then 1/R = 1/5 + 1/25.......R=4.16667 ohm

4. you should have given required angles.

- ?Lv 44 years ago
"How do you be conscious of what formulation to apply?" sometimes you do no longer, yet while the 1st element you do is attempt to locate the suited formulation, then certain you're doing the subject incorrect. Physics isn't the flexibility of looking up formulation in textbooks, neither is it plug-and-chug algebra. each equation describes a *courting between parts*, case in point, F=ma tells you approaches tension, mass, and acceleration are all interrelated. once you learn physics, do no longer look on the equations. pay attention on your professor and study the *textual content textile* in the *textual content textile*e book. Visualize on your recommendations which parts are related to which different parts and make up sentences to describe them, as in "greater tension ability greater acceleration, yet greater mass ability much less acceleration." In a particular undertaking, first of all continuously draw a image, label each little thing and write down what you be conscious of. Then think of the place the relationships can get you from the beginning factor. do no longer attempt to take a seat there and choose each step in enhance. in basic terms use the relationships between parts to clue you in to equations for you to use to acquire new parts that are with a bit of luck useful, despite in the event that they do no longer inspect present day functional. at last you will see your way with the aid of to the top of the subject.

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