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3 years ago

. Is there net work done on an object at rest or moving at a constant velocity? WHICH ONE ???

1 answer:

8 0

If an object is moving with a constant velocity, then by definition it has zero acceleration. So there is no net force acting on the object. The total work done on the object is thus 0 (that's not to say that there isn't work done by individual forces on the object, but the sum is 0 ).

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A 15 g ball at the end of 2.4 m string is swung in the horizontal circle. It revolves once every 2.09 s. What is the magnitude o

Mrrafil [7]

Answer:

0.325 N

Explanation:

From the question,

T = 4π²rm/t²............................ Equation 1

Where T = Tension, r = radius or length of the string, m = mass of the string, t = time.

Given: r = 2.4 m, m = 15 g = 0.015 kg, t = 2.09 s.

Constant: π = 3.14

Substitute these values into equation 1

T = 4(3.14²)(2.4)(0.015)/2.09²

T = 1.4198/4.3681

T = 0.325 N

3 0

3 years ago

A swing that is 9.2m long has a child in it who is swinging. what is its period in seconds

Fantom [35]

The child on a swing can be modeled as a simple pendulum. The period of a simple pendulum is given by

$T=2 \pi \sqrt{ \frac{L}{g} }=2 \pi \sqrt{ \frac{9.2m}{9.8 \frac{m}{s^2} } }=6.09s$

8 0

3 years ago

The intensity of light from a central source varies inversely as the square of the distance. If you lived on a planet only half

sertanlavr [38]

Answer:

the intensity will be 4 times that of the earth.

Explanation:

let us assume the following:

intensity of light on earth =J

distance of earth from sun = d

intensity of light on other planet = K

distance of other planet from sun = $\frac{d}{2}$ (from the question, the planet is half as far from the sun as earth)

from the question the intensity is inversely proportional to the square of the distance, hence

intensity on earth : J = $\frac{1}{d^{2} }$

J $d^{2}$ = 1 ... equation 1

intensity on other planet : K = $\frac{1}{(\frac{d}{2}) ^{2} }$ (the planet is half as far from the sun as earth)

K $(\frac{d}{2}) ^{2}$ = 1 ....equation 2

equating both equation 1 and 2 we have

J $d^{2}$ = K $(\frac{d}{2}) ^{2}$

J $d^{2}$ = K $\frac{d^{2}}{4}$

J = $\frac{K}{4}$

K = 4J

intensity of light on other planet (K) = 4 times intensity of light on earth (J)

5 0

3 years ago

The block in the drawing has dimensions L0×2L0×3L0,where L0 =0.5 m. The block has a thermal conductivity of 200 J/(s·m·C˚). In d

Dennis_Churaev [7]

Answer:

$Q_p=18000\ J$

$Q_o=8000\ J$

$Q_g=72000\ J$

Explanation:

Given:

Length of block, $l=3L_o=3\times 0.5=1.5\ m$

Breadth of block, $b=L_o=0.5\ m$

height of block, $h=2L_o=2\times 0.5=1\ m$

Thermal conductivity of the block, $k=200\ W.m.^{\circ}C$

Temperature on the hotter side, $T_H=37^{\circ}C$

temperature on the cooler side, $T_L=7^{\circ}C$

time for which the heat flows, $t=4\ s$

REFER THE ATTACHED IMAGE FOR THE REFERENCE

The rate of heat flow using Fourier's law of conduction is given as:

$\frac{Q}{t}=k.A.\frac{dT}{dx}$

Now the amount heat flow perpendicular to the pink surface:

$\frac{Q_p}{4}=200\times (0.5\times 1.5).\frac{30}{1}$

$Q_p=18000\ J$

Now the amount heat flow perpendicular to the orange surface:

$\frac{Q_o}{4}=200\times (0.5\times 1).\frac{30}{1.5}$

$Q_o=8000\ J$

Now the amount heat flow perpendicular to the green surface:

$\frac{Q_g}{4}=200\times (1.5\times 1).\frac{30}{0.5}$

$Q_g=72000\ J$

6 0

3 years ago

Can a molecule have bond dipoles but not have a molecular dipole?

MissTica

Answer: Yes

Explanation: A molecule has a bond dipole but not have a molecular dipole.

Dipole moment: dipole moment is the product of the distribution of the charge of the molecules and the distance between of the molecules.

Example:

lets take an example of $CO_{2}$ molecule in which two electro negative oxygen atoms are attached with Carbon atom. Oxygen being electro negative will attract the shared pair electrons towards itself and partial negative charge will create on oxygen atom and partial positive charge on carbon atom C.

due to formation of partial positive and partial negative charges dipole moment is created between oxygen and Carbon bond on both the sides in opposite direction.

Since, the dipole moment acting in opposite direction the net dipole moment in the molecule is zero.

Hence, Yes, a molecule has bond dipoles but not have a molecular dipole.

8 0

4 years ago