Electric/Gravitational Fields
If the electric field at a point between two charges is 0, what do you know about the charges?
They are both positive or negative.
They are not necessarily equal
What is the escape velocity?
The velocity required to never be pulled back toward the object.
There are very large numbers of charged particles in most objects. Why don't most objects exhibit static electricity?
The charges are balanced, positive to negative.
What type of field forms between two charged plates, like a capacitor?
uniform
q1, on the left has a charge of +8 uC. q2, on the right, has a charge of +4 uC. What direction will a positive test charge placed between them go?
q1 . q2
To the right.
Two satellites orbit Earth at the same distance above the surface. Satellite A is 3500 kg and satellite B is 7,000 kg. How does the velocity of satellite A compare to the velocity of satellite B?
They have the same velocity.
vA=vB
Calculate the weight of a 4,500 kg elephant on Earth
44,100 N
If a point charge is released from rest in a uniform electric field, will it follow a field line?
Will it do so if the electric field is not uniform?
Yes and yes. Field lines are the lines a charge would move.
What type of field does a capacitor have between its plates?
What type of field does a planet or star have?
a) Uniform
b) Radial
How does the orbital velocity of an object change as it gets further from its host?
A) the orbital velocity increases
B) the orbital velocity decreases
C) the orbital velocity stays the same
B, the orbital velocity decreases
A positively charged object attracts a small piece of cork.
a) Can we conclude that the cork is negatively charged?
b) The rod repels another piece of cork. Can we conclude that this piece is positively charged?
a) No, electrons can shift to one side and attract toward the rod.
b) Yes, must have some positive charge to be repelled.
Draw a field diagram for q1, a +6 uC charge and q2, a +12 uC charge 1 meter apart.
Field lines should point outwards
Field lines should point away from each other.
q2 should have twice as many field lines.
30 J of work is done to lift a 0.5 kg apple 3 meters from point A to point B. Determine the potential difference between these points.
60 J/kg
A new planet has a radius of 5.5 million meters and a Space Station is in orbit 400,000 meters above the planet.
Jorryn is a resident of the Space Station. Jorryn is going for a spacewalk after dark. He travels around the planet in 125 minutes. Determine Jorryn's velocity.
4,900 meters.
A +84 uC charge is placed 73 cm from a -34 uC charge.
Determine the force acting on each charge.
Is this an attractive or repulsive force?
-48 N
Attractive
Two charges are placed as shown. The negative charge is many times stronger than the positive charge. Where could a test charge be placed to have an electric field of 0 N/C?
+ --
To the left of the positive charge.
A +6 uC charge of mass, 2.3 E -9 kg, is placed in a uniform electric field. The mass accelerates at a rate of 4.5 E 3 m/s2. Determine the electric field strength acting on the charge.
1.73 N/C
Determine the escape velocity required for a 38,000 kg rocket if it is starting on Earth's surface. The Earth has a mass of 5.97 E 24 kg and a radius of 6.371 E 6 m.
11,200 m/s
Calculate the weight of a 850 kg horse on a satellite 400 km above the surface of the Earth. The mass of the Earth is 5.97 E 24 kg and the radius of the Earth is 6.371 E 6 m.
7,400 N
Three charges of the same magnitude are placed at the vertices of an equilateral triangle. Two of the charges are positive and one is negative. Draw the field lines between the three. Draw each charge with at least 6 field lines.
Field lines separate between the positive charges, but attract to the negative.