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ElenaW [278]
3 years ago
15

A dockworker loading crates on a ship finds that a 25-kg crate, initially at rest on a horizontal surface, requires a 72-N horiz

ontal force to set it in motion. However, after the crate is in motion, a horizontal force of 55 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.
Physics
1 answer:
Gnom [1K]3 years ago
7 0

Answer:

Explanation:

Force of static friction = μs x mg

Given force of static friction = 72 N

μs x mg = 72

μs = 72 / mg

= 72 / 25 x 9.8

= .294

Force of kinetic  friction = μk x mg

Given force of kinetic  friction = 55

μk x mg = 55

μk = 55 / mg

= 55 / 25 x 9.8

= .2245

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How does the configuration of the electric field occur between a "parallel plate" setup in a lab?What is the effect of conductor
sleet_krkn [62]

Explanation:

The magnitude of the electric field between the plates is given by

E = -ΔV/d

minus sign indicates Potential decreases in the direction of electric field

where

ΔV is the potential difference between the plates

D is the distance between the plates.

The work done when carrying an electrical charge on an equipotential surface between one position to the other is zero W= q(V-V)=0 The electric field lines of force are always perpendicular to an equipotential surface.  That conductor in an equipotential surface as direction E is at right angles to an eauipotential surface The intensity of the electric field along an equipotential surface is always zero. Equipotential surfaces never collide with each other as this would mean that at that point, there are two alternative values that are not true.

8 0
3 years ago
Charlie pulls horizontally to the right on a wagon with a force of 37.2 N. Sara pulls horizontally to the left with a force of 2
Sidana [21]

Answer:

The work done on the wagon is 37 joules.

Explanation:

Given that,

The force applied by Charlie to the right, F = 37.2 N

The force applied by Sara to the left, F' = 22.4 N

We need to find the work done on the wagon after it has moved 2.50 meters to the right. The net force acting on the wagon is :

F_n=F-F'

F_n=37.2-22.4

F_n=14.8\ N

Work done on the wagon is given by the product of net force and displacement. It is given by :

W=F_n\times d

W=14.8\ N\times 2.5\ m

W = 37 Joules

So, the work done on the wagon is 37 joules. Hence, this is the required solution.

7 0
3 years ago
Read 2 more answers
A 55 kg track and field athlete has an average power output of 5.4 kW during the 200 meter dash. How quickly did she finish the
olga_2 [115]

The time taken for the athlete to finish the race is 20 s (Option A)

<h3>What is power? </h3>

Power is simply defined as the rate at which work is done. It can be expressed mathematically as

Power (P) = work (W) / time (t)

But

Work = weight × distance

Therefore,

Power = (weight × distance ) / time

<h3>How to determine the time </h3>
  • Mass (m) = 55 Kg
  • Acceleration due to gravity (g) = 9.8 m/s²
  • Weight = mg = 55 × 9.8 = 539 N
  • Power (P) = 5.4 KW = 5.4 × 1000 = 5400 W
  • Distance (d) = 200 m
  • Time (t) =?

Power = (weight × distance ) / time

5400 = (539 × 200) / t

5400 = 107800 / t

Cross multiply

5400 × t = 107800

Divide both side by 5400

t = 107800 / 5400

t = 20 s

Learn more about power:

brainly.com/question/5684937

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5 0
2 years ago
There is a refrigerator running in a room, the heat flowing into the refrigerator from the outside is 40 J/s, and the refrigerat
Mamont248 [21]

Answer:

(A) 140 j/sec (b) 1.26 K

Explanation:

We have given the heat heat flowing into the refrigerator = 40 J/sec

Work done = 40 W

(a) So the heat discharged from the refrigerator =heat\ flowing\ in\ refrigerator+work\ done=40+100=140j/sec

(b) Total heat absorbed =140 j/sec =140\times 3600=504000j/hour

Let the temperature be \Delta T

Heat absorbed per hour =504000 [tex]=400\times 10^3\times \Delta T

So  \Delta T=\frac{504000}{400000}=1.26K

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Alex73 [517]
Infrared waves are used in heat lamps and other heat sensing devices. Infrared waves or commonly known as Infrared radiations (IR) is the type of electromagnetic radiation we encounter most in our everyday life. Heat lamps are electrical devices which emit infrared radiation.
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3 years ago
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