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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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An element's atomic number is the​
Zepler [3.9K]

the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus.

Hope this helped

8 0
3 years ago
Write equations for both the electric and magnetic fields for an electromagnetic wave in the red part of the visible spectrum th
Strike441 [17]

Answer:

E=3.5(8.98*10^{6}x-2.69*10^{15}t)

B=1.17*10^{-8}(8.98*10^{6}x-2.69*10^{15}t)

Explanation:

The electric field equation of a electromagnetic wave is given by:

E=E_{max}(kx-\omega t) (1)

  • E(max) is the maximun value of E, it means the amplitude of the wave.
  • k is the wave number
  • ω is the angular frequency

We know that the wave length is λ = 700 nm and the peak electric field magnitude of 3.5 V/m, this value is correspond a E(max).

By definition:

k=\frac{2\pi}{\lambda}            

k=8.98*10^{6} [rad/m]      

And the relation between λ and f is:                

c=\lambda f

f=\frac{c}{\lambda}

f=\frac{3*10^{8}}{700*10^{-9}}

f=4.28*10^{14}

The angular frequency equation is:

\omega=2\pi f

\omega=2\pi*4.28*10^{14}

\omega=2.69*10^{15} [rad/s]

Therefore, the E equation, suing (1), will be:

E=3.5(8.98*10^{6}x-2.69*10^{15}t) (2)

For the magnetic field we have the next equation:

B=B_{max}(kx-\omega t) (3)

It is the same as E. Here we just need to find B(max).

We can use this equation:

E_{max}=cB_{max}

B_{max}=\frac{E_{max}}{c}=\frac{3.5}{3*10^{8}}

B_{max}=1.17*10^{-8}T

Putting this in (3), finally we will have:

B=1.17*10^{-8}(8.98*10^{6}x-2.69*10^{15}t) (4)

I hope it helps you!

8 0
3 years ago
How can you determine the number of covalent bonds an element can form?
BabaBlast [244]
Yes it depends on the column on the periodic table
3 0
3 years ago
If an object is thrown in an upward direction from the top of a building 160 ft high at an initial speed of 30 mi/h, what is
expeople1 [14]

Answer:

We can use  2 g H = v2^2 - v1^2    or

v2^2 = 2 g H + v1^2

Since 88 ft/sec = 60mph   we have 30 mph = 44 ft/sec

The object will return with the same speed that it had initially so the object

starts out with a downward speed of 44 ft/sec

Then v2^2 = 2 * 32 ft/sec^2 * 160 ft + 44 (ft/sec)^2

v2^2 = (2 * 32 * 160 + 44^2) ft^2 / sec^2 = 12180 ft^2/sec^2

v2 = 110 ft/sec

8 0
3 years ago
Ángel is riding his bike 15m/h south a) speed b) velocity c) acceleration​
mixer [17]

Answer:

Velocity

Explanation:

Speed does not have a direction, Acceleration means that it is speeding up and not at a constant 15m/h, so the answer is B.

7 0
2 years ago
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