PLS PLS HURRY!!!! 50 points!!

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

3 years ago

The membrane that surrounds a certain type of living cell has a surface area of 4.3 x 10-9 m2 and a thickness of 1.1 x 10-8 m. A

Nadusha1986 [10]

Answer:

The charge resides on the outer surface = $1.245 \times 10^{-12}$ C

Explanation:

Surface area of cell $(A) = 4.3\times 10^{-9} m^{2}$

Separation between two plate $(d) = 1.1 \times 10^{-8} m$

Dielectric constant $(k) = 4.2$

Potential difference $(\Delta V) = 85.7 \times 10^{-3} V$

The capacitance of parallel plate capacitor in free space is given by,

$C = \frac{\epsilon_{o} A }{d}$

Where $\epsilon_{o} =$ permittivity of free space = $8.85 \times 10^{-12}$

The Capacitance of capacitor is increase by $k$ times when it placed in dielectric medium.

$C_{dielectric} = \frac{k \epsilon_{o} A }{d}$

And we know that, $C = \frac{Q}{ \Delta V}$

So charge on the outer surface is given by,

$Q = \frac{k \epsilon A \Delta V }{d}$

$Q = \frac{4.2 \times 4.3 \times 10^{-9} \times 8.85 \times 10^{-12} \times 85.7\times 10^{-3} }{1.1 \times 10^{-8} }$

$Q = 1.245 \times 10^{-12}$

3 0

3 years ago

PLEASE ANYONE SOLVE THIS NOW FAST PLEASE IM IN A HURRY

m_a_m_a [10]

Hello,

<u>Solution for A:</u>

Force = 3.00N

Mass = 0.50 Kgs

Time = 1.50 Seconds

According to newton's second law of motion;

Force = Mass times Acceleration(a)

3.00 = 0.50 * a

a = 3.00/0.50 = 6.00 m/s^2

We know that acceleration = Velocity / time

So Velocity = time * acceleration = 1.50 * 6 = 9.00 m/s^2

<u>Solution for B:</u>

The net force = 4.00N - 3.00N = 1.00N to the left

Force = 1.00N

Mass = 0.50Kg

Time = 3.00 Seconds

Again; F = MA (Where F is force, M is mass and A is acceleration)

1.00N = 0.5 * A

A = 1/0.5 = 2 m/s^2

Velocity = Acceleration * Time = 2 * 3 = 6 m/s

3 0

3 years ago

Amir and Gracie left some evidence of breakfast behind. Luckily, some of it can be changed back. What does Mosa write down as cl

marta [7]

Answer:

You could say that it was not a chemicly change because that is when you say this is just a example that if you cook eggs you cant un-cook them

Explanation:

3 0

2 years ago

Name and describe the three types of binary systems.

Pachacha [2.7K]

Answer and Explanation:

The binary system is a star system about half of the star are the part of the binary system

The important binary systems are

Visual binary : in visual binary system the two stars resolved visually with nay sort of optical device the orbit of binary orbit is very large about center of mass.
Spectroscopic binary : in this binary system the stars are detected by close analysis of light and after detection it is found that there are two seller spectrum present instead of one.
Eclipsing binary : eclipsing binary system is a several types of variable stars this binary system is very important in astrophysics

5 0

3 years ago