Stars and Space
What is a light year a measure of?
Distance (travelled by light in a vacuum in one year).
What force keeps planets in orbit around the Sun?
Gravity
Which Newton's Law states "For every action there is an equal and opposite reaction"?
Newton's Third Law.
What is the difference between static and current electricity?
Static electricity is a build-up of charge.
Current electricity is moving charge.
What is wavelength?
The distance between matching points on a wave.
What is the name of the stage where a star spends most of its life fusing hydrogen into helium?
Main sequence star
As the distance between two objects increases, what happens to the gravitational force?
It decreases.
A car travels at constant velocity. Are the forces balanced or unbalanced?
Balanced.
What does a voltmeter measure?
Voltage. - potential energy difference between two points
What is the rule for angle of reflection of a wave?
Angle of incidence = angle of reflection
Put these stages in order:
Red Giant, Main Sequence, Protostar, White Dwarf
Protostar → Main Sequence → Red Giant → White Dwarf
The gravitational force between two objects is 16 N. If the distance doubles, what is the new force?
4 N
A 1000 kg car accelerates at 2 m/s².
Calculate the net force.
F=ma
F = 1000 × 2 = 2000 N
Define what an ammeter measures?
How many electrons pass a point in one second.
(coulombs / second)
A wave has a frequency of 4 Hz and wavelength of 5 m.
Find the speed.
v = f λ
= 4 × 5 = 20 m/s
What is the difference between the final stages of a Sun-like star and a massive star?
A Sun-like star becomes a white dwarf after a planetary nebula.
A massive star becomes a supernova and may form a neutron star or black hole.
Why do satellites further from Earth generally have lower orbital speeds?
Gravity is weaker at greater distances, so less speed is needed to maintain orbit.
A car increases speed from 10 m/s to 30 m/s in 5 s.
Find the acceleration.
Acceleration = (30 − 10)/5 = 4 m/s²
A circuit has a voltage of 12 V and resistance of 6 Ω.
Find the current.
I=V/R
= 12.0V / 6.0Ω
=2.00A
In which medium does light travel fastest?
A vacuum.
A star has finished its supergiant stage. Describe the possible future stages and end products.
Supergiant → Supernova → Neutron Star OR Black Hole.
A satellite orbits Earth at a larger orbital radius than another satellite. Compare the gravitational force and orbital speed of the two satellites.
The satellite further away experiences less gravitational force and has a lower orbital speed.
A truck of mass 2000 kg accelerates from 5 m/s to 15 m/s in 4 s.
Calculate the acceleration and force.
a = (15 − 5)/4 = 2.5 m/s²
F = 2000 × 2.5 = 5000 N
A series circuit has two light bulbs, each with a current of 3 A and a voltage of 24 V.
Calculate the total resistance.
At each bulb
R = 24/3 = 8 Ω
Total Resistance = R1 +R2
= 8 + 8 = 16 Ω
What happens when light passes from a denser into a less dense medium at an angle?
It speeds up and bends away from the normal.