Homework Statement
A lens has a focal length of f=20cm. If an object is at o=50 cm, where is the image?
Homework Equations
1/f = 1/o + 1/i
The Attempt at a Solution
1/20 = 1/50 + 1/i
5/100 = 2/100 + 1/i
3/100 = 1/i
i = 100/3
I'm not sure how the answer could be 1/20...
Homework Statement
A concave mirror has a focal length of f=50 cm. If an object is at o=500cm, where is the image?
Homework Equations
1/f = 1/o + 1/i
The Attempt at a Solution
1/50 = 1/500 + 1/55.56
What I don't understand is "where is the image"? How do I interpret it from...
Homework Statement
The sun emits 3x1032J of energy every day. Assume it emits only yellow light (6x10-7m wavelength. a. What is the energy of each photon of yellow light? b. How many photons does the sun emit every day?
Homework Equations
E = hf
The Attempt at a Solution
So I think...
Homework Statement
If the average KWH used per month in a household is 1650KWH for the year, what is the average power consumption rate in watts that gives this average KWH energy value?
Homework Equations
KWH X 1000WH/1KWH = W?
The Attempt at a Solution
1650KWH x 1000WH/1kWH =...
Homework Statement
. Consider the energy of a 100 kg rock.
a) What is the gravitational potential energy (PE) of the rock that is 5 m above the ground?
b) The rock falls to the ground. What is its PE?
c) What is the change in PE of the rock?
d) What is the change in the kinetic...
Homework Statement
The sun outputs about 3.9x1026 W of power, a small fraction of which reaches the Earth’s surface. The sun provides about 100 W/m2 of power to the Earth’s surface averaged over time and weather. How much energy is deposited on average by the sun on Washington state in an...
Homework Statement
A car is traveling at a constant 60 miles per hour. What is its kinetic energy in Joules if its mass is 800 kg?
Homework Equations
KE = 1/2m * v2 (?)
The Attempt at a Solution
½(800kg)*(26.82 m/s)2 = 287,724 kg * m2/s2 = 287,724 J
I hope that looks right...