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Explanation:
Answer:
The average speed for the entire trip is 56 miles/hour.
Explanation:
It is given that,
Initially, the car moves with a speed of, v₁ = 40 miles/hour
Initial time, t₁ = 0.5 hours
Distance covered during time t₁,
![d_1=v_1t_1](https://tex.z-dn.net/?f=d_1%3Dv_1t_1)
![d_1=40\times 0.5](https://tex.z-dn.net/?f=d_1%3D40%5Ctimes%200.5)
![d_1=20\ miles](https://tex.z-dn.net/?f=d_1%3D20%5C%20miles)
Then it travels with a speed of, v₂ = 60 miles/hour
Then time taken, t₂ = 2 hours
Distance covered during time t₂,
![d_2=v_2t_2](https://tex.z-dn.net/?f=d_2%3Dv_2t_2)
![d_2=60\times 2](https://tex.z-dn.net/?f=d_2%3D60%5Ctimes%202)
![d_2=120\ miles](https://tex.z-dn.net/?f=d_2%3D120%5C%20miles)
The average speed of the car can be calculated as :
![v=\dfrac{d_1+d_2}{t_1+t_2}](https://tex.z-dn.net/?f=v%3D%5Cdfrac%7Bd_1%2Bd_2%7D%7Bt_1%2Bt_2%7D)
![v=\dfrac{120+20}{0.5+2}](https://tex.z-dn.net/?f=v%3D%5Cdfrac%7B120%2B20%7D%7B0.5%2B2%7D)
v = 56 miles/hour
So, the average speed of the car for the entire trip is 56 miles/hour. Hence, this is the required solution.
To make something electrical you need electricity and the wires will turn a magnet into an electromagnet.
or for a short answer: <span>1) soft iron core 2) coil of insulated wire 3)source of electricity</span>
Answer:
B) The car at point C has less kinetic energy than the car at point B.
Explanation:
We have two types of energy involved in this situation:
- Gravitational potential energy: this is the energy related to the heigth of the car, and it is given by
, where m is the mass of the car, g is the gravitational acceleration, and h is the heigth of the car. The potential energy is higher when the car is located higher above the ground.
- Kinetic energy: this is the energy due to the motion of the car, and it is given by
, where m is the mass of the car and v is its speed. The kinetic energy is higher when the speed of the car is higher.
- The law of conservation of energy states that the total mechanical energy of the car (sum of potential energy and kinetic energy:
) is constant). This implies that when the car is at a higher point, the kinetic energy is less (because U is larger, so K must be smaller), while when the car is at a lower point, the kinetic energy is larger.
- Based on what we have written so far, we can conclude that the correct statement is:
B) The car at point C has less kinetic energy than the car at point B.
Because the car at point C is located at a higher point than point B, so the car at point C has larger potential energy than at point B, which implies that car at point C has less kinetic energy than the car at point B.
Expanding and galaxies (and stars) are moving further away.