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3 years ago

How rolling friction is less than sliding friction?

1 answer:

6 0

Rolling friction is considerably less than sliding friction as there is no work done against the body that is rolling by the force of friction. For a body to start rolling a small amount of friction is required at the point where it rests on the other surface, else it would slide instead of roll.

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An AC generator has an output rms voltage of 100.0 V at a frequency of 42.0 Hz. If the generator is connected across a 45.0-mH i

Rus_ich [418]

Answer:

(a) 11.8692‬ ohm

(b) 12.447 A

Explanation:

a) inductive reactance Z = L Ω

= L x 2π x F

= 45.0 x 10⁻³ x 2(3.14) x 42

= 11.8692‬ ohm

b) rms current

= 100 / 8.034

= 12.447 A

c) maximum current in the circuit

= I eff x rac2

= 12.447 x 1.414

= 17.6 A

4 0

3 years ago

What are conductors and insulators? Give at least five example of each

Leona [35]

Answer: conductors are substances that allow heat or electricity to pass through . It deals with only the flow of electrons.

Eg. water, copper wire, iron rod, some ceramic materials, metallic nail.

Insulators are materials that do not allow heat or electricity to pass through.

Eg. Book, plastic, rubber, glass, paper

Explanation:

8 0

2 years ago

The following three hot samples have the same temperature. The same amount of heat is removed from each sample. Which one experi

vlabodo [156]

Answer:

Smallest drop: Water

Largest drop: Dirt

Explanation:

The heat needed to change the temperature of a sample is:

$Q=cm\Delta T$ (1)

with Q the heat (added(+) or removed(-)), c specific heat, m the mass and $\Delta T$ the change in temperature of the sample. So, if we solve (1) for

Sample A:

$\Delta T=-\frac{Q}{cm} =\frac{Q}{4186*4.0}$

$\Delta T=-\frac{Q}{16744}$

Sample B:

$\Delta T=-\frac{Q}{cm} =\frac{Q}{2700*2.0}$

$\Delta T=-\frac{Q}{5400}$

Sample C:

$\Delta T=-\frac{Q}{cm} =\frac{Q}{1050*9.0}$

$\Delta T=-\frac{Q}{9450}$

Note that the numbers 16744, 5400, 9450 are in the denominator of the expression $-\frac{Q}{cm}$ that gives the drop on temperature. so, if Q is the same for the three samples the smallest denominator gives the largest drop and vice versa.