Hypem
Member
- Joined
- Mar 13, 2013
- Messages
- 133
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- Male
- HSC
- 2013
I don't know how to work this one out.
15) In order to escape a planet's gravitational field, a projectile's initial velocity needs to be equal to the escape velocity.
During its escape the projectile's kinetic energy is transformed into gravitational potential energy.
A projectile is required to escape the gravitational field of planet X. Planet X has four times the radius and nine times the mass of the Earth.
Compared to the Earth, by what factor would the projectile's escape velocity have to change on planet x?
(A) 0.5 times
(B) 1.5 times (correct answer)
(C) 3 times
(D) 4 times
18) Two long parallel wires carry equal currents in the same direction. The magnitude of the force between the wires due to the currents is F.
The separation between the wires is now halved.
Which of the following describes the new force between the wires due to the same currents?
(A) Magnitude 2F and attractive (correct answer)
(B) Magnitude 2F and repulsive
(C) Magnitude 4F and attractive
(D) Magnitude 4F and repulsive
I thought it was (C) because F is proportional to 1/d^2 and hence halving would result in 4 times greater magnitude?
Note: Is this next one part of the Motors and Generators topic or Ideas to Implementation? Because that might explain why I don't know what to do.
19) A solid metallic disc is moved with constant velocity in the direction of the arrow across a uniform magnetic field.
(diagram shows a magnetic field going INTO the page, and the whole disc is in it, and the disc moving to the right). Point A is at the top (north), Point C is on the west side, and B on the south side.
The electrons in the disc experience a force due to the motor effect. Electrons are most likely to experience a force towards which labelled area of the metal?
(A) A
(B) B (correct answer)
(C) C
(D) Each area equally
15) In order to escape a planet's gravitational field, a projectile's initial velocity needs to be equal to the escape velocity.
During its escape the projectile's kinetic energy is transformed into gravitational potential energy.
A projectile is required to escape the gravitational field of planet X. Planet X has four times the radius and nine times the mass of the Earth.
Compared to the Earth, by what factor would the projectile's escape velocity have to change on planet x?
(A) 0.5 times
(B) 1.5 times (correct answer)
(C) 3 times
(D) 4 times
18) Two long parallel wires carry equal currents in the same direction. The magnitude of the force between the wires due to the currents is F.
The separation between the wires is now halved.
Which of the following describes the new force between the wires due to the same currents?
(A) Magnitude 2F and attractive (correct answer)
(B) Magnitude 2F and repulsive
(C) Magnitude 4F and attractive
(D) Magnitude 4F and repulsive
I thought it was (C) because F is proportional to 1/d^2 and hence halving would result in 4 times greater magnitude?
Note: Is this next one part of the Motors and Generators topic or Ideas to Implementation? Because that might explain why I don't know what to do.
19) A solid metallic disc is moved with constant velocity in the direction of the arrow across a uniform magnetic field.
(diagram shows a magnetic field going INTO the page, and the whole disc is in it, and the disc moving to the right). Point A is at the top (north), Point C is on the west side, and B on the south side.
The electrons in the disc experience a force due to the motor effect. Electrons are most likely to experience a force towards which labelled area of the metal?
(A) A
(B) B (correct answer)
(C) C
(D) Each area equally
