Homework Statement
A force F is used to raise a 4-kg mass M from the ground to a height of 5 m. What is the work done by the force F? (Note: sin60 = 0.87; cos60 = 0.5. Ignore friction and the weights of the pulleys.)
A) 50 J
B) 100 J
C) 174 J
D) 200 J
Please click here for picture.
Homework...
Homework Statement
Two adjacent allowed energies of an electron in a one-dimensional box are 2.0 eV and 4.5 eV. What is the length of the box?
Homework Equations
E_n=\frac{h^2n^2}{8mL^2}
The Attempt at a Solution
My question is, since E_n and n^2 are both on separate sides of the equation...
So I can't use I^2R, because by definition the current would also be a different value for a new R? But we know the voltage will stay the same for a new R, so we can use V^2/R?
Homework Statement
The average power dissipated by a resistor is 4.0 W. What is the average power if the resistance R is doubled?
Homework Equations
P_{rms}=I_{rms}^2R=I_{rms}V_{rms}=\frac{V_{rms}^2}{R}
The Attempt at a Solution
I am told the answer is 2.0 W. But here's what I am confused...
Homework Statement
The voltage across a 60μF capacitor is described by the equation vC =(18 V) cos(200t), where t is in seconds.
What is the voltage across the capacitor at t =0.010 s?
Homework Equations
N/A
The Attempt at a Solution
When you use degrees the answer is 18V and...
If I is the same for both resistors then according to P=I^2(R), R for the 60 W bulb must be higher.
But I am confused because according to P = V^2/R the 60 W has a higher R...how do I know which equation to use?
Homework Statement
Normally, household lightbulbs are connected in parallel to a power supply. Suppose a 40 W and a 60 W lightbulb are, instead, connected in series. (see here) Which bulb is brighter?
Homework Equations
P_{resistor}=I\Delta V=I^2R =\frac{(\Delta V)^2}{R}
The Attempt at a...
So if I'm not mistaken you can some them,
\Sigma R = R_{muscle} + R_{fat}
I think I can see why it would decrease now; just because more fat is being added doesn't make resistivity a bigger number. Fat was already present so the only number changing was A.
Thanks guys.
Homework Statement
A person gains weight by adding fat - and therefore adding girth - to his body and his limbs, with the amount of muscle remaining constant. How will this affect the electrical resistance of his limbs?
a. the resistance will stay the same
b. the resistance will...
Homework Statement
A 1.5 kg mass slides across a horizontal, frictionless surface at a speed of 2.0 m/s until it collides with and sticks to the free end of a spring with spring constant 50 N/m. The spring's other end is anchored to the wall. How far has the spring compressed when the mass, at...
Homework Statement
There's a picture with the problem attached
A block with mass m = 1.5 kg hangs to the right of two blocks with masses m2 = 2.2 kg and m1 = 1.2 kg which sit on a table. All three blocks are connected with a string and pulley. Neglecting the mass of the pulley, string and any...
Homework Statement
The driver of a car at 31 m/s sees (t = 0, x = 0) an obstacle down the road and brakes. The car slows down with a constant deceleration which has a magnitude of 6 m/s^2. Select the correct statement below (let d = stopping distance, all units are SI)
a. The position...
I figured it out. I forgot to to remember that the kid is on an incline, but how I drew it is having the X-axis horizontal, therefore there will not be any acceleration along the Y-axis.
SOLVED
Homework Statement
A 23 kg child goes down a straight slide inclined 38∘ above horizontal. The child is acted on by his weight, the normal force from the slide, and kinetic friction. Find the magnitude of the normal force.
Homework Equations
cos(theta)=adjacent/hypotenuse
The...
Homework Statement
Hello,
I have solved the problem, but not the way the writer intended. I need help figuring out how they wanted me to do it.
Here's the problem:
The circumference of a sphere is found to be 0.98 m +/- 0.01 m. Calculate the volume and absolute error with five digits...