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3 years ago

Ple help. 30 pts, do NOT steal points or get REPORTED ):

Physics

1 answer:

Viktor [21]3 years ago

5 0

Explanation:

sorry I'm late

I'm answering cause I felt bad abt the fact that noone answered u. Have a great morning or night!

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4. Identify Problems A student is describing a longitudinal wave in his notebook. He

andrew11 [14]

Answer:

"The distance between crests is 3 cm."

Explanation:

If he writes down "The distance between crests is 3 cm."

That means he is describing the wavelength of a wave and not longitudinal wave. He ought to write something about " direction "

Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or parallel to, the direction of propagation of the wave. While

Wavelength is the distance between the two successfully Crest or trough

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3 years ago

What is the normal force acting on a 2.8 kg object that is being dragged across a floor

enot [183]

Answer is in the file below

tinyurl.com/wpazsebu

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3 years ago

A horizontal force of magnitude 31.3 N pushes a block of mass 4.30 kg across a floor where the coefficient of kinetic friction i

Ostrovityanka [42]

Answer:

$W_{F} = +119.6 J$ : Work done by horizontal force

$W_{Ff} = -96.42 J$ : Work done by friction force

$W_{n} = 23.18 J$ : Net work

Explanation:

Work theory

Work is the product of a force applied to a body and the displacement of the body in the direction of this force.

Thus. The work is equal to the product of the force by the distance (d) and by the cosine of the angle ( α) that exists between the direction of the force (F) and the direction that travels the point or the object that moves:

W= F*d*cosα Formula (1)

The work is positive (W+) if the force goes in the same direction of movement.

The work is negative (W-)if the force goes in the opposite direction to the movement

Net work (Wn)

Net work is defined as the sum of the work done from an initial place to an end point of the trajectory, for each of the individual forces to which the system is subjected.

Problem development

We determine the forces that perform work:

in formula (1 )we observe that the forces that perform work are the forces parallel to displacement. that is α = 0.

For this case they are the horizontal force (F) and the frictional force (Ff)

F=31.3 N : Horizontal force

Ff=μk*N , μk:coefficient of kinetic friction , N : Normal force

N=W

W: block weight W= m*g, m: block mass , g: acceleration due to gravity

W= 4.30 kg* 9.8 m/s² = 42.14 N

Ff= 0.599*42.14 N= 25.24 N : Frictional force

Calculating of the Net work (Wn)

$W_{n} = W_{F} +W_{Ff}$