Calculating Power of a Light Bulb

In summary, a 100 watt light bulb uses 360,000 Joules of energy per hour. To have the same amount of kinetic energy, a 70-kg person would have to run at a speed of 5142.86 m/s. The formula used to calculate this is ke = 1/2 m v^2, where ke stands for kinetic energy, m is mass, and v is velocity. The units must be squared in order to get the correct result.
  • #1
Jim4592
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0

Homework Statement


How many Joules of energy does a 100 watt light bulb use per hour? How fast would a 70-kg person have to run to have that same amount of kinetic energy?


Homework Equations


How fast would a 70-kg person have to run to have the same amount of kinetic energy?


The Attempt at a Solution



1 watt = 1 J/S so... 100 J/S * 3600s = 360,000 J

360,000 kg m^2/s^2 ÷ 70 = 5142.86 m^2/s^2

my only question would be do you just square root the value and would it remove both ^2?
 
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  • #2
Yes a sqrt() acts on the units as well as the number
I think you are missing a factor 2 somewhere, ke = 1/2 m v^2
 
  • #3
ok thanks for your help, I'm pretty sure i can handle it from here.
 

1. How is the power of a light bulb calculated?

The power of a light bulb is calculated by multiplying the voltage of the bulb by the current flowing through it. This can be represented by the equation P = VI, where P is power in watts, V is voltage in volts, and I is current in amperes.

2. What is the unit of measurement for the power of a light bulb?

The unit of measurement for the power of a light bulb is watts (W). This is a measure of the rate at which energy is used or generated by the bulb.

3. How does the power of a light bulb affect its brightness?

The power of a light bulb directly affects its brightness. In general, the higher the wattage, the brighter the bulb will be. However, other factors such as bulb type and design can also influence brightness.

4. Can the power of a light bulb be changed?

Yes, the power of a light bulb can be changed by using a different voltage or by using a dimmer switch. However, it is important to note that changing the power of a light bulb may also affect its brightness and lifespan.

5. How do I determine the power of a light bulb if it is not labeled?

If the power of a light bulb is not labeled, you can use a multimeter to measure the voltage and current of the bulb and then calculate the power using the equation P = VI. Alternatively, you can refer to the manufacturer's specifications or consult a professional for assistance.

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