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2 years ago

If you place a hot block of metal in room temperature water is it convection or conduction?

2 answers:

4 0

The answer is Conduction: the process of heat is directly transmitted through a substance when there is a difference in temperature.

jonny [76]2 years ago

3 0

Answer:

convection

Explanation:

Convection is a process by which heat is transferred by the movement of a heated fluid such as air or water.

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A ball is projected at an angle of elevation of 60 ° with an initial velocity of 120m/s.calculate

Mrac [35]

Explanation:

It is given that,

The angle of projection is 60 degrees

Initial velocity of the ball is 120 m/s

We need to find the time taken to get to the maximum height and the time of flight.

Time taken to reach the maximum height is given by :

$T=\dfrac{u^2\sin^2\theta}{2g}$

g is acceleration due to gravity

$T=\dfrac{(120)^2\times \sin^2(60)}{2\times 10}\\\\T=540\ s$

(ii) Time of flight,

$t=\dfrac{2u\sin\theta}{g}$

So,

$t=\dfrac{2\times 120\times \sin(60)}{10}\\\\t=20.78\ s$

Hence, this is the required solution.

3 0

3 years ago

When there is a change of state, such as a solid to liquid or liquid to gas, heat energy can be added without a temperature chan

Romashka-Z-Leto [24]

I’m pretty sure the answer is C. Any change of state or movement requires energy

3 0

3 years ago

The moon has a diameter of 3.48 x 106 m and is a distance of 3.85 x 108 m from the earth. The sun has a diameter of 1.39 x 109 m

Mrrafil [7]

Answer:

0.00903 rad

0.00926 rad

6.268\times 10^{-6}

Explanation:

s = Diameter of the object

r = Distance between the Earth and the object

Angle subtended is given by

$\theta=\frac{s}{r}$

For the Moon

$\theta_m=\dfrac{3.48\times 10^6}{3.85\times 10^8}\\\Rightarrow \theta_m=0.00903\ rad$

The angle subtended by the Moon is 0.00903 rad

For the Sun

$\theta_s=\dfrac{1.39\times 10^9}{1.5\times 10^{11}}\\\Rightarrow \theta_s=0.00926\ rad$

The angle subtended by the Sun is 0.00926 rad

Area ratio is given by

$\frac{A_m}{A_s}=\dfrac{\pi r_m^2}{\pi r_s^2}\\\Rightarrow \frac{A_m}{A_s}=\dfrac{d_m^2}{d_s^2}\\\Rightarrow \frac{A_m}{A_s}=\dfrac{(3.48\times 10^{6})^2}{(1.39\times 10^9)^2}\\\Rightarrow \frac{A_m}{A_s}=6.268\times 10^{-6}$

The area ratio is $6.268\times 10^{-6}$

3 0

3 years ago

A girl exerts a horizontal force of 109 N on a crate with a mass of 31.2 kg. HINT (a) If the crate doesn't move, what's the magn

vesna_86 [32]

Answer:

(a) Magnitude of static friction force is 109 N

(b) Minimum possible value of static friction is 0.356

Solution:

As per the question;

Horizontal force exerted by the girl, F = 109 N

Mass of the crate, m = 31.2 kg

Now,

(a) To calculate the magnitude of static friction force:

Since, the crate is at rest, the forces on the crate are balanced and thus the horizontal force is equal to the frictional force, f:

F = f = 109 N

(b) The maximum possible force of friction between the floor and the crate is given by:

$f_{m} = \mu_{s}N$

where

N = Normal reaction = mg

Thus

$f_{m} = \mu_{s}mg$

For the crate to remain at rest, The force exerted on the crate must be less than or equal to the maximum force of friction.

$f\leq f_{m}$

$f \leq \mu_{s}mg$

$109 \leq \mu_{s}\times 31.2\times 9.8$

$\mu_{s}\geq 0.356$

7 0

3 years ago

If you weigh 38 kilograms on your bathroom scale, your weight in space will be ________.

harina [27]

Answer:

Less than 36kilo's

Explanation:

5 0

2 years ago