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Get the assessment: FA16.1.docx
Get the Practice Problems: Worksheet-ProblemsFromA16.1.docx
The Assessment solved:
1. What is the force on, and the electric field surrounding (magnitude and direction) an electron if it is accelerated upward at 5.20x1015 m/s/s?
(4.74x10-15 N up, 2.96x104 N/C down)
(Like Practice 1-5 below)
2. A 1.50-gram object is suspended against gravity between two horizontal parallel plates that are 5.20 cm apart. What charge does the object have if this requires 537 V to accomplish? If the top plate is negative, is the charge positive or negative?
(+1.42 µC, positive)
3. Two point masses have a force of attraction of 2.30x10-12 N when they are separated by 56.0 cm. What is their separation if the force of attraction is 5.80x10-12 N?
(35.3 cm)
(Like Practice 11-20 below)
4. Find the net force and direction on mass A and mass B:
(A: 10.8 N right, B: 1.72 N left)
More problems like this one:
Charge Array:
Mass Array:
(Like Practice 21 below)
5. Each grid line is a meter. Charge A is +160. µC, and charge B is -210. µC, and C is +630. µC. Calculate the force on charge A. Draw the force vector and label its magnitude and direction.
(144 N left and up at 68.4o above the x-axis)
<--- Ben Nickle's treatise on how to do all of this using matrices!!
More Practice Problems:
Problems from A16.1: Vector Forces - (Links are video solutions)
F = ma
1. An electron is in a 2310 N/C electric field to the West. What is its acceleration? Look up the charge and mass in your data packet. (4.06x1014 ms-2 East)
2. A proton accelerates North at 3.80x1012 ms-2. What is the electric field? (3.97x104 N/C North)
3. There is a upward force of 0.0120 N on a charge inside a downward electric field of 450. N/C. What is the charge? Is it positive or negative? (-2.67x10-5 C, negative)
4. The planet Xzarr exerts a force of 67.0 N on a 4.50 kg mass. What is the gravitational field strength? (14.9 N/kg)
5. A region in space has a gravitational field strength of 1.40 N/kg. What mass would experience a force of 780. N. (557 kg)
(Electrical force upwards = Gravitational force downwards) About these problems in General (video)
6. A 0.310-gram object with a charge of -1.80 mC is suspended against gravity between two horizontal parallel plates. The plates have a voltage of 150. V across them, what is their separation? Which plate is the positive plate? (8.88 cm, top)
7. A 0.980-gram object with a charge of +0.780 mC is suspended against gravity between two horizontal parallel plates that are 3.80 cm apart. What voltage does this require, and which plate is the positive plate? (468 V, bottom)
8. A 0.450-gram object is suspended against gravity between two horizontal parallel plates that are 1.50 cm apart. What charge does the object have if this requires 13.0 V to accomplish? If the top plate is negative, is the charge positive or negative? (5.09 µC, positive)
9. An object with a charge of +4.50 mC is suspended against gravity between two horizontal parallel plates that are 1.4 cm apart. What mass does the object have if this requires 260. V to accomplish? Which plate is positive, the top or the bottom? (8.52 g, bottom)
10. A 2.30 gram object is suspended against gravity between two horizontal parallel plates that are 3.80 cm apart. What charge does the object have if this requires 75.0 V to accomplish? If the positive plate is on the top, is the charge positive or negative? (11.4 µC (1.14x10-5 C), negative)
- Inverse square force laws
11. At what distance from the center of a 3.40 µC charge is there a force of 7.80 N on a 1.10 µC charge? Is it attracted or repelled? (6.57 cm, repelled)
12. A -3.80 µC charge is attracted with a force of 45.0 N to another charge that is 56.0 cm away. What is the other charge? Is it positive or negative? (413 µC(4.13x10-4 C), positive)
13. At what distance from the center of a 5.97x1024 kg planet is the force of attraction on a 6.00 kg mass 23.0 N (1.02x107 m)
14. On the surface of a 7.30x106 m radius planet, there is a 57.0 N force on a 5.10 kg mass. What is the planet's mass? (8.93x1024 kg)
15. Two point charges have a force of attraction of 140. N when they are 12.0 m away from each other. What is their force of attraction when they are 17.0 m away from each other? (69.8 N)
16. The force of gravity between two spherical masses is 5.90x10-12 N when their centers are separated by 1.80 m. If they are moved so that the force of attraction is 7.80x10-12 N, what is their new separation? (1.57 m)
17. Two point charges have a force of repulsion of 56.0 N when they are 45.0 cm from each other. At what separation is the force 98.0 N? (34.0 cm)
18. The force of gravity between two spherical masses is 6.00x10-11 N when their centers are separated by 1.10 m. If they are moved so that their separation is 3.20 m, what is the force of attraction? (7.09x10-12 N)
19. Two point charges have a force of attraction of 160. N when they are 2.50 m apart. If they are moved so their new force of attraction is 240. N, what is their separation? (2.04 m)
20. Two point masses are attracted by a force of 1.20x10-12 N when they are 45.0 cm apart. If they are moved so that they are 150.0 cm apart, what is their new force of attraction? (1.08x10-13 N)
21. Linear Arrays:
a) Find the net force and direction on the charges (A: 72.4 N right, B: 111 N left, C: 39.0 N right)
b) Find the net force and direction on the charges: (A: 12.2 N left, B: 91.1 N right, C: 78.9 N left)
c) Find the net force and direction on the masses: (A: 39.2 N right, B: 3.10 N left, C: 36.1 N left)
d) Find the net force and direction on the masses: (A: 10.5 N right, B: 11.9 N right, 22.4 N left)
22. Non-Linear Arrays:
Each grid line is a meter. Calculate the force on object A. Draw the force vector and label its magnitude and direction.
a) A is +160. µC, and B is -110. µC, and C is +630. µC.
(200. N up and left at 61.6o above the x-axis)
b) A is 1.60x106 kg, and B is 2.10x106 kg, and C is 6.30x106 kg.
(88.2 N right and down at 38.1o below the x-axis)
c) A is +560. µC, and B is +780. µC, and C is +450. µC.
d) A is 3.50x106 kg, and B is 2.20x106 kg, and C is 8.10x106 kg.
e) A is -680. µC, and B is -890. µC, and C is +670. µC.
(273 N down and to the right at 85.8o below the x-axis)
f) A is 1.50x106 kg, and B is 7.30x106 kg, and C is 5.10x106 kg.
(61.6 N right and up at 20.3o above the x-axis)
Instruction for this unit:
1. Force and electric field and acceleration
2. force = gravity
3. Coulomb's law
4. Linear force arrays
12:25 Forces in Nonlinear Charge Arrays 2
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