Enery phisic question

  • Thread starter RMHAZARD
  • Start date
  • #1
24
0
hi here is the question

A 60 watt light bulb is left swithed on for 10 hours. If the light bulb is 15% effcient, calculate the amount of light energy produced in that time. what is the total energy consumption of the light bulb in this time.

so i need to find work done right so is that power divided by time to get the energy and then find 15% of that am i right i am bathed by this.
 

Answers and Replies

  • #2
Kurdt
Staff Emeritus
Science Advisor
Gold Member
4,812
6
A watt is 1 unit of energy per unit time. You know how much of the energy was turned into light (15%) and the length of time the light was left on. No need to introduce work.
 
  • #3
24
0
so do i divide watts by time taken?
 
  • #4
24
0
so 60 watts divided by10 hours which is 6 15% of 6 is 0.9 if i am correct

can you please tell me if i am right if not can you advive me where i went wrong
 
  • #5
Kurdt
Staff Emeritus
Science Advisor
Gold Member
4,812
6
your answer is incorrect. First you need to think about units
watts is per second whereas you're given a time in hours. Secondly do you think the energy would be lower or higher than how much you are using in one second?
 
  • #6
24
0
so 10 hours is 600 minutes 36000 seconds and 60 watts goes goes in in 36000 2160000 so 15% 324000 am i right
 
  • #7
Kurdt
Staff Emeritus
Science Advisor
Gold Member
4,812
6
Correct. now remember to state you units. energy is measured in.....
 

Related Threads on Enery phisic question

  • Last Post
Replies
1
Views
953
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
1K
Replies
3
Views
3K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
6
Views
1K
  • Last Post
Replies
6
Views
3K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
5
Views
2K
Top