Answer: D. decreasing the temperature
Explanation:
The kinetic energy is 945 joules.
Kinetic energy is the energy that an object has as a result of motion. It is defined as the effort required to accelerate a mass-determined body from rest to the indicated velocity.
The speed of an object or particle, which is a scalar quantity, is the size of the change in its location over time or the size of the change in its position per unit of time.
The mass of the volleyball is 2.1 kg.
The speed of the ball when the ball leaves the hand is 30 m/s.
m = 2.1 kg
v = 30 m/s
The kinetic energy of an object is given as:
KE = (1/2 ) × m × v²
KE = (1 / 2) × 2.1 kg × ( 30 m/s)²
KE = (1 / 2) × 2.1 kg × 30 m/s × 30 m/s
KE = 2.1 kg × 15 m/s × 30 m/s
KE = 945 J
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Answer:
B) Power
Explanation:
The power is defined by the following equation:
P = W / t
where:
W = work = Force * Distance = [Newton] * [meter]
t = time = seconds
The units for work are give en Newton per second, which is equal to Joules
And for power the unit used commonly is Watts, therefore:
Watts = (Joule/second)
C. Thick wire and cold temperature.
Explanation:
The resistance of a wire is given by: R = (ρL)/A
where ρ is the resistivity of the material, L is the length of the wire, A is the cross-sectional area of the wire.
From the formula, we see that the thicker the wire, the larger A, therefore the smaller the resistivity. so, a thick wire will have lower resistivity.
Moreover, the resistance of a wire increases with the temperature. In fact, high temperatures mean more motion of the atoms/electrons inside the wire, so more resistance to the flow of current through it. Therefore, colder temperature means lower resistance.
So, the correct option is thick wire and cold temperature.
