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1 year ago

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A constant power is supplied to a rotating disc .the relationship of angular velocity of disc and number of rotations made by th

e disc is governed by

1 answer:

Bogdan [553]1 year ago

6 0

A rotating disc supplied with constant power where the relationship of the angular velocity of the disc and the number of rotations made by the disc is governed by Newton's second law for rotation. This law is specially made for rotating bodies which is extracted from Newton's second law of motion.

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A 120-g block of copper is taken from a kiln and quickly placed into a beaker of negligible heat capacity containing 300 g of wa

gavmur [86]

Answer : The correct option is, (d) $535^oC$

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

where,

$c_1$ = specific heat of copper = $0.10cal/g^oC$

$c_2$ = specific heat of water = $1.00cal/g^oC$

$m_1$ = mass of copper = 120 g

$m_2$ = mass of water = 300 g

$T_f$ = final temperature of mixture = $35^oC$

$T_1$ = initial temperature of copper = ?

$T_2$ = initial temperature of water = $15^oC$

Now put all the given values in the above formula, we get:

$120g\times 0.10cal/g^oC\times (35-T_1)^oC=-300g\times 1.00cal/g^oC\times (35-15)^oC$

$T_1=535^oC$

Therefore, the temperature of the kiln was, $535^oC$

7 0

2 years ago

Read 2 more answers

Three particles are moving perpendicular to a uniform magnetic field and travel on circular paths (see the drawing). They have t

Vaselesa [24]

Explanation:

Radius of a charged particle is given by

r=mv / Bq

= k/ q

where k = m v / B is a constant.

i.e. more is the magnitude of charge, less is the radius. (inversely proportional)

From the diagram r_3 > r_2 > r_1 (more the curvature, less is the radius)

( although drawing is not given i am assuming the above order, however, one can change the order as per the diagram. The concept used remains the same)

therefore, q_1 > q_2 > q_3 .

7 0

2 years ago

Nastasia [14]

Answer:

8 cm

Ladder is safer than to walk on it

Explanation:

Streched = Final length - initial length

= 66 - 58

= 8 cm

When your are walking along frozen ice pond your weight is not distributed .It's acting on directly on the ice pond because of contact Area is too small between pond and you. There for According to pressure equation ,

P = F/A

When area is less pressure is less.

If use ladder instead of going by foot. Contact area will be high between pond and ladder. There for pressure is reduced .

3 0

2 years ago

When you skid to a stop on your bike, you can significantly heat the small patch of tire that rubs against the road surface. Sup

Wittaler [7]

Answer:

$W_f = 148.17J$

Explanation:

During the exchange of applied force, thermal energy is generated by the friction that exists between the ground and the tire.

Said force according to the statement is the reaction of half the force on the rear tire. In this way the normal force acted is,

$N=\frac{mg}{2} = \frac{90*9.8}{2} = 441N$

The work done is given by the friction force and the distance traveled,

$W_f = fd = \mu_k Nd$

Where $\mu_k [/ tex] is the coefficient of kinetic frictionN is the normal force previously found d is the distance traveled,Replacing,[tex]W_f = (0.80)(441)(0.42)$

The thermal energy released through the work done is,

$W_f = 148.17J$

3 0

1 year ago

8. The resistance of a bagel toaster is 14 Ω. To prepare a bagel, the toaster is operated for one minute from a 120-V outlet. Ho

IgorC [24]

Answer: The energy delivered to the toaster is 264.490KJ

Explanation:

Here is the complete question:

The resistance of a bagel toaster is 14 ?. To prepare a bagel, the toaster is operated for one minute from a 120-V outlet. How much energy is delivered to the toaster?

Step-by-step explanation:

Please see attachment below

7 0

1 year ago

Read 2 more answers