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3 years ago

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

Physics

1 answer:

frozen [14]3 years ago

3 0

Answer:

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

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What do you make when you dissolve sugar in water?

AlladinOne [14]

It also takes energy to break the hydrogen bonds in water that must be disrupted to insert one of these sucrose molecules into solution. Sugar dissolves in water because energy is given off when the slightly polar sucrose molecules form intermolecular bonds with the polar water molecules.

I hope this helped :)

5 0

3 years ago

A block of mass m=16.8 kg is sliding on a surface with initial velocity v=23.2 m/s. The block has a coefficient of kinetic frict

Firdavs [7]

Answer:

t = 23.92 s

Explanation:

Newton's second law:

∑F = m*a Formula (1)

∑F : algebraic sum of the forces in Newton (N)

m : mass s (kg)

a : acceleration (m/s²)

We define the x-axis in the direction parallel to the movement of the block and the y-axis in the direction perpendicular to it.

Forces acting on the block

W: Weight of the block : In vertical direction, downward

FN : Normal force : perpendicular to the floor, upward

fk : Kinetic friction force: parallel to the floor and opposite to the movement

F = 86.4 N , in the direction of the motion

Calculated of the W

W= m*g

W= 16.8 kg* 9.8 m/s² = 164.64 N

Calculated of the FN

We apply the formula (1)

∑Fy = m*ay ay = 0

FN - W = 0

FN = W

FN = 164.64 N

Calculated of the fk

fk = μk*FN

fk = 0.426* 164.64 N

fk = 70.13 N

We apply the formula (1) to calculated acceleration of the block:

∑Fx = m*ax , ax= a : acceleration of the block

F - fk = m*a

86.4 -70.13 = (16.8)*(-a)

16.26 = (16.8)*(-a)

a = -(16.26 )/ (16.8)

a = - 0.97 m/s²

Kinematics of the block

Because the block moves with uniformly accelerated movement we apply the following formula :

vf = v₀ + a*t Formula (2)

Where:

t: time interval (m)

v₀: initial speed (m/s)

vf: final speed (m/s)

Data:

v₀ = 23.2 m/s

vf = 0

a = -0.97 m/s²

Time it takes for the block to stop

We replace data in the formula (2) to calculate the time

vf= v₀+a*t

0 = 23.2+( -0.97)*t

(0.97)*t = 23.2

t = 23.2 / (0.97)

t = 23.92 s

7 0

3 years ago

2) Light reflects off of surfaces. It is also absorbed by opaque materials

Lunna [17]

Answer: B

White paper reflects some of the incoming waves,

while black absorbs all of the incoming waves.

Explanation:

Light is reflected off of white surfaces. Light is absorbed by opaque materials and transmitted through transparent objects.

In the case of a white paper, a white paper can be considered as a translucent material in which some of the light incident on it bounces off while some pass through it. Therefore, we can conclude that White paper reflects some of the incoming waves,

while black absorbs all of the incoming waves.

6 0

3 years ago

What is one way to take advantage of creating even more kinetic energy on this particular technologically advanced field

ch4aika [34]

Incomplete question. However, I provided a brief about Kinetic energy generation.

<u>Explanation:</u>

Interestingly, Kinetic energy in simple terms refers to the energy possessed by a body in motion.

It is often calculated using the formula E = $\frac{1}{2}MV^{2}$

A good example of creating even more kinetic energy is a hand crank toy car that moves after you wind it a little, when the car moves it is generating another measure of K.E.

7 0

3 years ago

A child does 350 J of work while pulling a box from the ground up to his tree house at a steady speed with a light rope. The tre

777dan777 [17]

Answer:

8.929kg

Explanation:

The work done to place the box at tree house=350 J.

The distance from ground to tree house =4.0 m and $g=9.8m/s^2$