A teacher performing demonstration finds that a piece of cork displaces 23.5 ml of water. The piece of cork has a mass 5.7 g. Wh
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Answer:
<em>The person delivered a power of 2,558 Watt</em>
Explanation:
<u>Work and Power</u>
Mechanical work is the amount of energy transferred by a force. It's a scalar quantity, with SI units of joules.
Being the force vector and the displacement vector, the work is calculated as:
If both the force and displacement are parallel, then we can use the equivalent scalar formula:
W=F.s
Power is the amount of energy transferred per unit of time. In the SI, the unit of power is the watt, equivalent to one joule per second.
The power can be calculated as:
Where W is the work and t is the time.
If the person lifts a mass of m=200 Kg, then exerts a force equal to its weight:
F = m.g = 200*9.8 = 1,960
F = 1,960 N
The work done when lifting the weight 7 times by a distance of s=2.2 m is:
W = 7*1,960*2.2=30,184
W = 30,184 J
Finally, the power delivered in t=11.8 seconds is:
P = 2,558 Watt
The person delivered a power of 2,558 Watt
The heat required to change 1.25 kg of steak is 2825 kJ /kg.
<u>Explanation</u>:
Given, mass m = 1.25 kg, Temperature t = 100 degree celsius
To calculate the heat required,
Q = m L
where m represents the mass in kg,
L represents the heat of vaporization.
When a material in the liquid state is given energy, it changes its phase from liquid to vapor and the energy absorbed in this process is called heat of the vaporization. The heat of vaporization of the water is about 2260 kJ/kg.
Q = 1.25 2260
Q = 2825 kJ /kg.