7. A car moving at 10m/s (about 22.4 mph) crashes into a barrier and stops in 0.25 m.
1 answer:
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Answer:
A kilowatt (kW) is a unit of power.
Explanation:
The power of an object is given by :
Here,
E is the energy required
t is time
The SI unit of power is Watts and the SI unit of energy is Joule. the commercial unit of energy is kilowatt per hour.
Option (1) : A kilojoule (kJ) is a unit of power is incorrect.
Option (2) : A gigawatt (GW) is a unit of energy is incorrect.
Option (3) : A watt (W) is a unit of energy is incorrect.
Option (4) : A kilowatt x hour per year (kWh/yr) is a unit of energy is incorrect.
Option (4) : A kilowatt (kW) is a unit of power is correct.
Hence, the correct option is (d).
The time taken for the two balls to hit each other is 8 s.
The given parameters:
- <em>Acceleration of the rocket, a = 2 m/s²</em>
- <em>Length of the chamber, s = 4 m</em>
- <em>Speed of the first ball, = V1 = 0.3 m/s</em>
- <em>Speed of the second ball, V2 = 0.2 m/s</em>
The time taken for the two balls to hit each other is calculated by applying relative velocity formula as shown below;
Thus, the time taken for the two balls to hit each other is 8 s.
Learn more about relative velocity here: brainly.com/question/17228388