Given :
Initial speed , u = 0 m/s .
Final speed , v = 91 km/h = 25.28 m/s .
To Find :
a) Average acceleration .
b ) Assuming the motorcycle maintained a constant acceleration, how far is it from the traffic light after 3.3 s .
Solution :
a )
We know ,by equation of motion :
![v^2-u^2=2as\\\\a=\dfrac{v^2-u^2}{2s}\\\\a=\dfrac{25.28^2-0^2}{2\times 47}\ m/s^2\\\\a=6.8\ m/s^2](https://tex.z-dn.net/?f=v%5E2-u%5E2%3D2as%5C%5C%5C%5Ca%3D%5Cdfrac%7Bv%5E2-u%5E2%7D%7B2s%7D%5C%5C%5C%5Ca%3D%5Cdfrac%7B25.28%5E2-0%5E2%7D%7B2%5Ctimes%2047%7D%5C%20m%2Fs%5E2%5C%5C%5C%5Ca%3D6.8%5C%20m%2Fs%5E2)
b)
Also , by equation of motion :
![s=ut+\dfrac{at^2}{2}\\\\s=0+\dfrac{6.8\times (3.3)^2}{2}\ m\\\\s=37.02\ m](https://tex.z-dn.net/?f=s%3Dut%2B%5Cdfrac%7Bat%5E2%7D%7B2%7D%5C%5C%5C%5Cs%3D0%2B%5Cdfrac%7B6.8%5Ctimes%20%283.3%29%5E2%7D%7B2%7D%5C%20m%5C%5C%5C%5Cs%3D37.02%5C%20m)
Hence , this is the required solution .
At critical temperature, the resistivity of the superconductor
B. It suddenly drops to zero
Explanation:
Materials can be classified into three different types depending on their resistance:
- Conductors: these materials have generally low resistance and allow electricity to pass through easily. The resistance of a conductor increases linearly with the temperature
- Insulators: these materials do not allow electricity to pass through - so they have very high resistance
- Semi-conductors: these are materials that are insulators are room temperature, however they becomes conductors when heated. Therefore, the resistance of a semiconductor decreases when the temperature increases
- Superconductors: these are special materials that are normally conductors; however, at very low temperatures (we are talking about temperature very near to 0 K), their resistance becomes suddenly zero.
Therefore, the correct answer is:
B. It suddenly drops to zero
Learn more about current and resistance:
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Answer:
22.02 m
Explanation:
given,
Force, F = 107 N
angle made with horizontal = 13.5◦
Power develop by the lawn roller = 69.4 W
time = 33 s
distance = ?
Force along horizontal= F cos θ
= 107 cos 13.5°= 104 N
Power = ![\dfrac{work\ done}{time}](https://tex.z-dn.net/?f=%5Cdfrac%7Bwork%5C%20done%7D%7Btime%7D)
69.4 = ![\dfrac{W}{33}](https://tex.z-dn.net/?f=%5Cdfrac%7BW%7D%7B33%7D)
W = 2290.2 J
Work done= Force x displacement
displacement= ![\dfrac{2290.2}{104}](https://tex.z-dn.net/?f=%5Cdfrac%7B2290.2%7D%7B104%7D)
= 22.02 m
C. Voltage.
Voltage is sometimes called electrical potential.