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3 years ago

14

What are some physical properties of a star

2 answers:

Juli2301 [7.4K]3 years ago

8 0

Distance, how much energy generated in the star, size, temp, brightness

zloy xaker [14]3 years ago

7 0

1. Apparent magnitude
2. Colur Index
3. Annual parallax/variation period if it is Cepheid variable/Red Shift
4. Radial Velocity & Tangential Velocity
Other quantities are derived from the above basic observational data.

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What role does actin and myosin play in the process of muscle contraction?

Margarita [4]

Answer:

Muscle contraction thus results from an interaction between the actin and myosin filaments that generates their movement relative to one another. The molecular basis for this interaction is the binding of myosin to actin filaments, allowing myosin to function as a motor that drives filament sliding.

4 0

1 year ago

Thermal energy is added to four identical samples of water what increases in each sample

Setler [38]

Thermal energy is added to four identical<span> 1.0 kg </span>samples of water<span> at room temperature. Which of the following </span>increases in each sample<span>? average charge of an electron; average density of </span>a<span> nucleus; average mass of </span>a<span> proton; average speed of </span>a<span> molecule. Your answer: -. Answer: D - average speed of </span>a<span>molecule.</span>

8 0

2 years ago

Read 2 more answers

You push very hard on a heavy desk, trying to move it. You do work on the desk:

frozen [14]

Answer:

(C) Only if it starts moving

Explanation:

We know that work done is given by

$W=F.d=Fdcos\Theta$

So there are two case in which work done is zero

First case is that when force and displacement are perpendicular to each other

And other case is that when there is no displacement

So for work to be done there must have displacement, if there is no displacement then there is no work done

So option (c) will be the correct option

3 0

2 years ago

How many ohms of resistance must be present in a circuit that has 240 volts and a current of 15 amps?

PIT_PIT [208]

Answer:

16 ohms

Explanation:

V= I ⋅ R

where, V is the net potential difference in the circuit, I is the current in the circuit and R is the net resistance of the circuit.

In this case, V = 240 volts, I = 15 amperes.

240 = 15 ⋅ R

⇒ R = 240/ 15 = 16 ohms

5 0

3 years ago

Read 2 more answers

The energy from 0.015 moles of octane was used to heat 250 grams of water. The temperature of the water rose from 293.0 K to 371

arsen [322]

Answer : The correct option is, (B) -5448 kJ/mol

Explanation :

First we have to calculate the heat required by water.

$q=m\times c\times (T_2-T_1)$

where,

q = heat required by water = ?

m = mass of water = 250 g

c = specific heat capacity of water = $4.18J/g.K$

$T_1$ = initial temperature of water = 293.0 K

$T_2$ = final temperature of water = 371.2 K

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

$q=250g\times 4.18J/g.K\times (371.2-293.0)K$

$q=81719J$

Now we have to calculate the enthalpy of combustion of octane.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy of combustion of octane = ?

q = heat released = -81719 J

n = moles of octane = 0.015 moles

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

$\Delta H=\frac{-81719J}{0.015mole}$

$\Delta H=-5447933.333J/mol=-5447.9kJ/mol\approx -5448kJ/mol$

Therefore, the enthalpy of combustion of octane is -5448 kJ/mol.

5 0

3 years ago