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NemiM [27]
3 years ago
15

A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on

it. the coefficient of kinetic friction between the crate and the floor is 0.25. (a) what magnitude of force must the worker apply
Physics
1 answer:
Olin [163]3 years ago
5 0
The crate moves at constant velocity, this means that its acceleration is zero, so the net force acting on the crate is zero (Newton's second law). 

There are only two forces acting on the crate: the force F applied by the worker and the frictional force, acting in the opposite direction: \mu m g, where \mu=0.25 is the coefficient of friction and m=30.0 kg is the mass of the crate. Since the net force should be equal to zero, the two forces must have same magnitude, so we have:
F=\mu m g=(0.25)(30.0 kg)(9.81 m/s^2)=73.8 N
And so, this is the force that the worker must apply to the crate.
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Un cubo de madera de densidad 0.780 g/cm³ mide 11.2 cm en un lado. Cuando se coloca en agua, ¿qué altura del bloque flotará sobr
Stolb23 [73]

Answer:

2.464 cm above the water surface

Explanation:

Recall that for the cube to float, means that the volume of water displaced weights the same as the weight of the block.

We calculate the weight of the block multiplying its density (0.78 gr/cm^3) times its volume (11.2^3  cm^3):

weight of the block = 0.78 * 11.2^3  gr

Now the displaced water will have a volume equal to the base of the cube (11.2 cm^2) times the part of the cube (x) that is under water. Recall as well that the density of water is 1 gr/cm^3.

So the weight of the volume of water displaced is:

weight of water = 1 * 11.2^2 * x

we make both weight expressions equal each other for the floating requirement:

0.78 * 11.2^3 = 11.2^2 * x

then x = 0.78 * 11.2 cm = 8.736 cm

This "x" is the portion of the cube under water. Then to estimate what is left of the cube above water, we subtract it from the cube's height (11.2 cm) as follows:

11.2 cm - 8.736 cm = 2.464 cm

6 0
3 years ago
An object has a mass of 30 grams and measures 3cmx2cmx1cm. What is the density of the object?
dimulka [17.4K]
The density of the object is the ratio of its mass and volume. From the given dimensions above, we determine the volume through the equation,

      V = L x W x H

Substituting,

    V = (3 cm)(2 cm)(1 cm) = 6 cm³

From the idea presented above,
    d = m/V

Substituting the known values,

   d = (30 g)/ (6 cm³) = 5 g/cm³

ANSWER: 5 g/cm³
4 0
3 years ago
When passing through a lock, which light means âapproach the lock under full control?â?
vekshin1
The locks referred to here are the elevators that are used to transport boats safely from one water level to another in dams. These two varying water depths allow river traffic to operate  The attached picture shows how boats enter locks in dam sites.

To regulate traffic, there are traffic lights that signal boatmen to adjust their speed when approaching the lock. The red light means to stop and to steer clear away from the lock to allows the boats inside to exit. The green light signals to enter the lock. Lastly, the amber light means approach the lock at a safe speed and under full control.

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3 years ago
If 2.0 j of work is requiered to move 4 c of chsrge between two points in an electric firld, what is the potential difference be
djverab [1.8K]
2 J / 4 C = 1/2 joule per coulomb.

That's 1/2 volt.
5 0
3 years ago
Explain how the Indian and Asian plates met and the kind of boundary that formed on their meeting. Describe what happened as a r
ANEK [815]

Answer:

This immense mountain range began to form between 40 and 50 million years ago, when two large landmasses, India and Eurasia, driven by plate movement, collided. ... Artist's conception of the 6,000-km-plus northward journey of the "India" landmass (Indian Plate) before its collision with Asia (Eurasian Plate).

Explanation:

4 0
3 years ago
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