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Vinvika [58]
2 years ago
12

How is a light element like helium is formed in stars and how is a heavier element like gold formed by stars?

Physics
1 answer:
aliina [53]2 years ago
7 0

Answer:

C

Explanation:

Because *censored*. Then the element *censored* your answer

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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
SIZIF [17.4K]

(a) 73.5 N

The velocity of the crate is constant: this means that the acceleration is zero (a=0), so according to Newton's second law

\sum F = ma

the resultant of the forces must be zero: \sum F = 0 (1)

The motion is along the horizontal direction, so we are only interested in the forces acting along this direction. There are two of them:

F, the push applied by the worker

F_f=-\mu mg, the force of friction, with \mu=0.25 being the coefficient of friction, m=30.0 kg being the mass of the crate, and g=9.8 m/s^2. The negative sign is due to the fact that the friction acts in the opposite direction to the motion. Eq.(1) then becomes

F-\mu mg=0\\F=\mu mg=(0.25)(30.0 kg)(9.8 m/s^2)=73.5 N

So, this is the force that the worker must apply.

(b) 330.8 J

The work done by the pushing force of the worker on the crate is given by:

W=Fd cos \theta

where

F = 73.5 N is the force

d = 4.5 m is the displacement

\theta=0^{\circ} is the angle between the direction of the force and the displacement (0 degrees, since they are in same direction)

Substituting, we have

W=(73.5 N)(4.5 m)(cos 0^{\circ})=330.8 J

(c) -330.8 J

To calculate the work done by friction, we apply the same formula:

W=F_f d cos \theta

where

F_f = \mu mg=(0.25)(30.0 kg)(9.8 m/s^2)=73.5 N is the magnitude of the force of friction

d = 4.5 m is the displacement

\theta=180^{\circ} is the angle between the direction of the force of friction and the displacement (it is 180 degrees since the two are into opposite directions)

Substituting, we find

W=(73.5 N)(4.5 m)(cos 180^{\circ})=-330.8 J

So, the work done by friction is negative.

(d) 0 J

As before, the work done by any force on the crate is

W=F_f d cos \theta

We notice that both gravity and normal force are perpendicular to the displacement: therefore, \theta=90^{circ}, and so

cos \theta=0

which means that the work done by both forces is zero.

(e) 0 J

The total work done on the crate is the sum of the work done by the four forces acting on it, so:

W=W_{push} + W_{friction}+W_{gravity}+W_{normal}=330.8J-330.8J+0+0=0

And this is in accordance with the work-energy theorem, which states that the variation of kinetic energy of the crate is equal to the work done on it: since the crate is moving at constant velocity, its variation of kinetic energy is zero, as well as the work done on it.

5 0
3 years ago
On Mars, where air resistance is negligible, an astronaut drops a rock from a cliff and notes that the rock falls about d meters
dimulka [17.4K]

Answer:

d_1 = 16 d

Explanation:

As we know that initial speed of the fall of the stone is ZERO

v_i = 0

also the acceleration due to gravity on Mars is g

so we have

d = v_i t + \frac{1}{2}gt^2

now we have

d = 0 + \frac{1}{2}g t^2

now if the same is dropped for 4t seconds of time

then again we will use above equation

d_1 = 0 + \frac{1}{2}g(4t)^2

d_1 = 16(\frac{1}{2}gt^2)

d_1 = 16 d

7 0
3 years ago
Read 2 more answers
In the equation Ca(s) + 2H2O(l) -->Ca(OH)2(aq) + H2(g) list each element used as a reactant, and tell how many atoms of each
Mekhanik [1.2K]

The reactants are <em>Calcium</em>, <em>Hydrogen</em> and <em>Oxygen</em>.

We need 1 atom of <em>Calcium</em>, 4 atoms of <em>Hydrogen</em> and 2 atoms of <em>Oxygen</em>.

Hope this helps.

r3t40

3 0
3 years ago
Which statement accurately describes the ultraviolet catastrophe
castortr0y [4]

Answer: A hot lightbulb gave off white visible light instead of ultraviolet light.

Explanation:

3 0
3 years ago
You're using a wedge to split a log. you are hitting the wedge with a large hammer to drive it into the log. it takes a force of
KIM [24]
The work performed on an object is the force multiplied by the distance it is moved, provided the movement is parallel to the force.  Since that is the case here, we can get the work by W=Fd=1900N x 0.23m = 437J.  This energy is used to split the wood.
6 0
3 years ago
Read 2 more answers
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