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aleksandr82 [10.1K]
2 years ago
6

Heres some earned points

Physics
2 answers:
irina1246 [14]2 years ago
6 0

Answer:

wait again? okay well how was ur day?

Explanation:

egoroff_w [7]2 years ago
5 0

Answer:

what do you mean by that.

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Sound is faster than light that is why we hear thunder before we see lightning
Umnica [9.8K]

Answer:

false

Explanation:

sound travels slower than light. that is why we see lightning before we hear the thunder

8 0
3 years ago
Sharks also swim in waters off the coast of Nova Scotia. When gray seals and harbor seals see sharks nearby, they must swim away
Vlada [557]
No. The seals are responding to a stimulus. 
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3 years ago
A brick of mass 5 kg is released from rest at a height of 3 m. How fast is it going when it hits the ground? Acceleration due to
sineoko [7]

Taking into account the definition of kinetic, potencial and mechanical energy, when the brick hits the ground, it has a speed of 7,668 m/s.

<h3>Kinetic energy</h3>

Kinetic energy is a form of energy. It is defined as the energy associated with bodies that are in motion and this energy depends on the mass and speed of the body.

Kinetic energy is defined as the amount of work necessary to accelerate a body of a given mass and at rest, until it reaches a given speed. Once this point is reached, the amount of accumulated kinetic energy will remain the same unless there is a change in speed or the body returns to its state of rest by applying a force.

The kinetic energy is represented by the following expression:

Ec= ½ mv²

Where:

  • Ec is the kinetic energy, which is measured in Joules (J).
  • m is the mass measured in kilograms (kg).
  • v is the speed measured in meters over seconds (m/s).

<h3>Potential energy</h3>

On the other hand, potential energy is the energy that measures the ability of a system to perform work based on its position. In other words, this is the energy that a body has at a certain height above the ground.

Gravitational potential energy is the energy associated with the gravitational force. This will depend on the relative height of an object to some reference point, the mass, and the force of gravity.

So for an object with mass m, at height h, the expression applied to the gravitational energy of the object is:

Ep= m×g×h

Where:

  • Ep is the potential energy in joules (J).
  • m is the mass in kilograms (kg).
  • h is the height in meters (m).
  • g is the acceleration of fall in m/s².
<h3>Mechanical energy</h3>

Finally, mechanical energy is that which a body or a system obtains as a result of the speed of its movement or its specific position, and which is capable of producing mechanical work. Then:

Potential energy + kinetic energy = total mechanical energy

<h3>Principle of conservation of mechanical energy </h3>

The principle of conservation of mechanical energy indicates that the mechanical energy of a body remains constant when all the forces acting on it are conservative (a force is conservative when the work it does on a body depends only on the initial and final points and not the path taken to get from one to the other.)

Therefore, if the potential energy decreases, the kinetic energy will increase. In the same way, if the kinetics decreases, the potential energy will increase.

<h3>This case</h3>

A brick of mass 5 kg is released from rest at a height of 3 m. Then, at this height, the brick of mass has no speed, so the kinetic energy has a value of zero because it depends on the speed or moving bodies. But the potential energy is calculated as:

Ep= 5 kg× 9.8 \frac{m}{s^{2} }× 3 m

Solving:

<u><em>Ep= 147 J</em></u>

So, the mechanical energy is calculated as:

Potential energy + kinetic energy = total mechanical energy

147 J +  0 J= total mechanical energy

147 J= total mechanical energy

The principle of conservation of mechanical energy  can be applied in this case. Then, when the brick hits the ground, the mechanical energy is 147 J. In this case, considering that the height is 0 m, the potential energy is zero because this energy depends on the relative height of the object. But the object has speed, so it will have kinetic energy. Then:

Potential energy + kinetic energy = total mechanical energy

0 J +  kinetic energy= 147 J

kinetic energy= 147 J

Considering the definition of kinetic energy:

½  5 kg×v²= 147 J

v=\sqrt{\frac{2x147 J}{5 kg} }

v=7.668 m/s

Finally, when the brick hits the ground, it has a speed of 7,668 m/s.

Learn more about mechanical energy:

brainly.com/question/17809741

brainly.com/question/14567080

brainly.com/question/12784057

brainly.com/question/10188030

brainly.com/question/11962904

#SPJ1

6 0
1 year ago
Which of the following is an exercise myth?
Margaret [11]
The answere is No pain, no gain
8 0
3 years ago
Read 2 more answers
Use the mass spectrum of europium to determine the atomic mass of europium. where the peak representing eu-151 has an exact mass
slavikrds [6]

Answer: The atomic mass of a Europium atom is 151.96445 amu.

From the given information:

Percent intensity is 91.61% of Europium atom of molecular weight 150.91986 amu.

Percent intensity is 100.00% of Europium atom of molecular weight 152.92138 amu.

Abundance of Eu-151 atom:

X_{Eu-151}=\frac{0.9161}{0.9161+1.000}=0.4781

Abundance of Eu-153 atom:

X_{Eu-153}=\frac{1.000}{0.9161+1.000}=0.5219

Atomic mass of Europium atom:

A=(X_{Eu-151}\times150.91986+X_{Eu-153}\times152.92138)amu\\A=(0.4781\times150.91986+0.5219\times152.92138)amu=151.96445 amu

Therefore, the atomic mass of a Europium atom is 151.96445 amu.

3 0
3 years ago
Read 2 more answers
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