The power in an electrical circuit is given by the equation P = I2R, where I is the current flowing through the circuit and R is
2 answers:
Since we are given the equation P = I2R and the measures of variables in the equation, our first step is to identify each variable.
Since there is a resistance of 30 ohms, R = 30Ω.
Since there is power of 2 watts, P = 2 W.
The variable we are trying to solve for is I, current.
Now we can plug the given information into the equation and solve for I:
Current (I) = 1/30 A, or 0.033 A.
Hope this helps!
Since there is a resistance of 30 ohms, R = 30Ω.
Since there is power of 2 watts, P = 2 W.
The variable we are trying to solve for is I, current.
Now we can plug the given information into the equation and solve for I:
Current (I) = 1/30 A, or 0.033 A.
Hope this helps!
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Answer: (2) Use the Momentum Principle.
Explanation:
In fact, it is called the <u>Conservation of linear momentum principle,</u> which establishes the initial momentum of the asteroids before the collision must be equal to the final momentum
after the collision, no matter if the collision was elastic or inelastic (in which the kinetic energy is not conserved).
In this sense, the linear momentum of a body is defined as:
Where is the mass and
the velocity.
Therefore, the useful approach in this situation is<u> option (2)</u>.
Answer:
a) The initial total mechanical energy of the projectile is 498556.296 joules.
b) The work done on the projectile by air friction is 125960.4 joules.
c) The speed of the projectile immediately before it hits the ground is approximately 82.475 meters per second.
Explanation:
a) The system Earth-projectile is represented by the Principle of Energy Conservation, the initial total mechanical energy () of the project is equal to the sum of gravitational potential energy (
) and translational kinetic energy (
), all measured in joules:
(Eq. 1)
We expand this expression by using the definitions of gravitational potential energy and translational kinetic energy:
(Eq. 1b)
Where:
- Mass of the projectile, measured in kilograms.
- Gravitational acceleration, measured in meters per square second.
- Initial height of the projectile above ground, measured in meters.
- Initial speed of the projectile, measured in meters per second.
If we know that ,
,
and
, the initial mechanical energy of the earth-projectile system is:
The initial total mechanical energy of the projectile is 498556.296 joules.
b) According to this statement, air friction diminishes the total mechanical energy of the projectile by the Work-Energy Theorem. That is:
(Eq. 2)
Where:
- Initial total mechanical energy, measured in joules.
- FInal total mechanical energy, measured in joules.
- Work losses due to air friction, measured in joules.
We expand this expression by using the definitions of gravitational potential energy and translational kinetic energy:
(Eq. 2b)
Where:
- Mass of the projectile, measured in kilograms.
- Gravitational acceleration, measured in meters per square second.
- Maximum height of the projectile above ground, measured in meters.
- Current speed of the projectile, measured in meters per second.
If we know that ,
,
,
and
, the work losses due to air friction are:
The work done on the projectile by air friction is 125960.4 joules.
c) From the Principle of Energy Conservation and Work-Energy Theorem, we construct the following model to calculate speed of the projectile before it hits the ground:
(Eq. 3)
Where:
- Total mechanical energy of the projectile at maximum height, measured in joules.
- Potential gravitational energy of the projectile, measured in joules.
- Kinetic energy of the projectile, measured in joules.
- Work losses due to air friction during the upward movement, measured in joules.
We expand this expression by using the definitions of gravitational potential energy and translational kinetic energy:
(Eq. 3b)
If we know that ,
,
,
and
, the final speed of the projectile is:
The speed of the projectile immediately before it hits the ground is approximately 82.475 meters per second.