Basic Physics
The unit for acceleration
m/s2
A circuit contains a cell, switch and lamp connected in series. What happens to the current when the switch is opened?
No current flow because the circuit is broken.
What is the relationship between charge, current and time?
Q = It
What is the equation relating force, mass and acceleration?
F = ma
What equation relates wave speed, frequency and wavelength?
v = fλ
If an object is at rest, what is its velocity?
0 m/s
Two identical lamps are connected in parallel to a battery. One lamp breaks. What happens to the other lamp?
It remains lit because it has its own complete branch.
A current of 3.0 A flows for 4 minutes. Calculate the charge transferred.
Q = 720 C
What is the difference between speed and velocity?
Speed is a scalar quantity; velocity is speed in a specified direction.
A wave has a frequency of 50 Hz and a wavelength of 2 m. Calculate its speed.
v = 100 m/s
The unit for velocity
m/s
Explain why household appliances are generally connected in parallel rather than series.
Each appliance receives the full supply voltage and can operate independently. Switching off/failure of one appliance does not stop the others.
A resistor has a resistance of 12 Ω and carries a current of 2.0 A. Calculate the potential difference across it.
V = 24 V
An object is moving at constant velocity. What can you say about the resultant force acting on it?
The resultant force is zero.
Why can light travel through a vacuum but sound cannot?
Light is an electromagnetic wave and does not require a medium. Sound is a mechanical wave and requires particles to transfer vibrations.
What is the acceleration formula?
a=(V-U)/t
A student replaces a 5 A fuse with a 13 A fuse because the 5 A fuse keeps blowing. Explain why this is dangerous.
The circuit may be drawing too much current. A 13 A fuse allows a larger current to flow before breaking the circuit, potentially causing overheating or fire.
A 60 W lamp operates from a 240 V supply. Calculate the current through the lamp.
I = 0.25 A
What does the second law of newton indicate?
The force of an object is equal to the mass times the acceleration of the object, or, the acceleration of an object is equal to the force divided by the mass.
A sound wave has a frequency of 500 Hz. What happens to its wavelength if the speed of sound remains constant but the frequency doubles?
Since v = fλ, wavelength is inversely proportional to frequency.
The wavelength halves.
The distance a car travelled if it drove at 40 m/s for 30 minutes (Convert to km)
72 km?
D = v*t = 40 m/s * 1800 s
D= 72,000 m = 72 km
A person touches the metal casing of a faulty appliance. Explain how the earth wire and fuse together protect the person.
A fault can cause current to flow through the metal casing. The earth wire provides a low-resistance path to ground, producing a large current that causes the fuse to melt and disconnect the supply.
A heater has a resistance of 48 Ω and is connected to a 240 V supply.
a) the current
b) the power of the heater
a) I = V/R
= 240/48
= 5 A
b) P = VI
= 240 × 5
= 1200 W
Tyler runs the basketball court 5 times (from one side back to the other 5 times). Ending in his original starting place. What is Tyler's displacement at the end of his run?
0 meters. He ended where he started
A ray of light travels from air into glass at an angle.
Explain what happens to:
a) its speed
b) its direction
c) its frequency
d) its wavelength
a) Speed decreases.
b) It changes direction/refracts towards the normal.
c) Frequency remains constant.
d) Wavelength decreases.