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Lesson: Capacitance & Capacitors
Solve the problem:
The two metal objects in the figure below have net charges of +70 pC and -70 pC, which result in a 20 V potential difference between them. (a) What is the capacitance of the system? (b) if the charges are changed to +200 pC and -200pC, what does capacitance become? (c) What does the potential difference become?
An automobile engine has an efficiency of 20% and produces 6000 J work. Find
the heat rejected by the engine.
A demonstration Van de Graaff generator has a 15 cm-diameter metal sphere that produces a voltage of 110 kV near its surface (Figure 5). What excess charge resides on the sphere? (k= 9 × 10⁹ Nm²/c²)
A box with a weight of 1260 N was dragged across the horizontal floor by a man by pulling a rope that is tied on the box. The man exerts a force of F= 485N on the rope, which is inclined at an angle of = 25o and the floor exerts a friction force of 98N on the box.
Find the following:
a. Draw the free-body diagram of the box.
b. The magnitude of the acceleration of the box.
c. Find the coefficient of friction
d. Find the normal force by the floor to the box.
1. An elevator cab that weighs 27.8 kN moves upward. What is the tension in the cable if the cab’s speed is ___.
Find the mass of the elevator:
a. At rest
b. Uniform motion
c. Increasing at a rate of 1.2m/s2
d. Decreasing at the rate of 1.2m/s2
Please give me a solution and formula by letters. Thank you!
A 2.5 KG MASS AND A 4 KG MASS ARE ATTACHED TO A LIGHT
WEIGHT CORD THAT PASSES OVER A FRICTIONLESS PULLEY. THE
HANGING MASSES ARE LEFT FREE TO MOVE. FIND THE
A 5000 KG TRUCK IS RUNNING AT 72 KPH.
a. ) IF IT IS TO BE STOPPED BY A CONSTANT RETARDING
FORCE IN 10 S. WHAT IS THE DECELERATION ?
b ) WHAT IS THE RETARDING FORCE ?
A particle moves in a straight line such that its displacement, x meters, from a fixed point O on the line at time t seconds is given by 𝑥 = 40[𝑒 −2𝑡 − 𝑒 −4𝑡 ].
(a) Find the time when the particle is instantaneously at rest.
(b) Find the displacement of the particle from O when t = 3 s.
(c) Find the total distance travelled during the first 3 seconds of its motion
THE SPEED OF 5 KG BODY IS TO BE INCREASED FROM 10
M/S TO 20 M/S. WHAT CONSTANT FORCE IS NEEDED TO
PRODUCE THIS CHANGE IN SPEED IN EXACTLY 5 S ?
A car’s tachometer indicates the angular velocity of the engine’s crankshaft in rpm. A car stopped
at a traffic light has its engine idling at 500 rpm. When the light turns green, the crankshaft
rotation speeds up at a constant rate to 2500 rpm in a time interval of 3.0 s. How many
revolutions does the crankshaft make in these time interval?
