Quiz on P3A

A moment is
1. a short period of time
2. the turning effect of a force
3. the mass x velocity
4. the change in momentum
The Principle of Moments says that:
1. moments are conserved in collisions involving turning objects.
2. moments are conserved in collisions involving objects moving in a straight line.
3. anticlockwise moments = clockwise moments when the turning object is balanced.
4. the turning effect is in the direction of the largest (principle) moment
Which one of these statements is true for the centre of mass?
1. It is always within the body of an object, no matter what shape.
2. Only regular objects have a centre of mass
3. The object has to have a line of symmetry for there to be a centre of mass.
4. It is an imaginary point where all the mass is concentrated
An object with a low centre of mass is lying on its side. When it's pushed, it rolls. It is said to be in
1. stable equilibrium
2. neutral equilibrium
3. unstable equilibrium
4. negative equilibrium
The centre of mass of an irregular sheet of material is best found by:
1. allowing the object to hang freely from one point, and drawing a vertical line from that point.
2. allowing the object to hang freely from two points, and drawing a vertical line from those points. Where the lines meet is where the centre of mass is.
3. allowing the object to hang freely from three points, and drawing a vertical line from those points. Where the lines meet is where the centre of mass is.
4. trying to find the point where it balances on a pin.
For a bus to be stable, it needs to have:
1. a low centre of mass and wide wheel-track
2. a low centre of mass and narrow wheel-track
3. a high centre of mass and wide wheel-track
4. a high centre of mass and narrow wheel-track
The force associated with circular motion is called
1. gravity
2. tension
3. centrifugal force
4. centripetal force
Which one of these changes does NOT cause an increase in centripetal force?
1. increasing the speed
2. increasing the radius
3. decreasing the radius
4. increasing the mass
When a car goes round a corner, which one of these provides the centripetal force?
1. The forward force from the engine.
2. The force from the brakes
3. The friction from the road surface.
4. The electromotive force from the battery
A toy aeroplane is tethered to a pole and is flying in a horizontal circle. The string breaks. What is its path now?
1. Vertically into the ground
2. A straight line along the radius of the circle.
3. A spiral outwards
4. A straight line at a tangent of the circle.
Which one of these statements is correct about gravity?
1. It has an infinite range and is always attractive.
2. It has an infinite range and can be attractive or repulsive.
3. It has a range of about three times the diameter of a planet and is always attractive.
4. It has a range of about three times the diameter of a planet and can be attractive or repulsive.
When a satellite is orbiting a planet, the centripetal force is provided by:
1. magnetism
2. electrostatic attraction
3. gravity
4. none of the above
Cosmonauts in a spacecraft in orbit feel weightless because
1. there is no gravity.
2. their spacecraft is falling at the same rate as the cosmonauts
3. the pull of gravity on the Earth is balanced by the pull of gravity from the spacecraft.
4. the cosmonauts have zero mass in space.
A spacecraft fires its main rocket motor. This will result in:
1. its going into a lower orbit but faster.
2. its going into a lower orbit and slower.
3. its going into a higher orbit and faster.
4. its going into a higher orbit, but slower
Tides occur because of the:
1. gravitational attraction of the Moon
2. gravitational attraction of the Earth
3. gravitational attraction of the Sun
4. vacuum in space attempting to suck all the water up.
A geostationary satellite orbits the Earth once every:
1. 30 minutes
2. 24 hours
3. 365 days
4. It doesn't; it stays in exactly the same place.
Which one of these satellites is most likely to be in a geostationary orbit?
1. weather satellite.
2. spy satellite.
3. a spacecraft carrying cosmonauts.
4. communications satellite.
In optics, the normal line is:
1. the line that the incident ray normally takes
2. the surface of the glass
3. a line at 90 degrees to the surface of the glass
4. a line at 90 degrees to the incident ray.
The image in a mirror is:
1. virtual and laterally inverted
2. real and laterally inverted
3. real and inverted
4. virtual and inverted
Lateral inversion means:
1. the image is upside down and back to front
2. the image is upside down and left is left and right is right.
3. the image is the right way up and left is left and right is right.
4. the image is right way up but left is right and right is left.
A virtual image is one that
1. can be projected onto a screen
2. cannot be projected onto a screen
3. has disappeared
4. is generated by a computer.
The image in a convex mirror is:
1. inverted, virtual, and diminished.
2. upright, real, and diminished.
3. upright, virtual, and diminished.
4. upright, virtual, and magnified.
The object seen through a lens is 4 cm high. Its image is 16 cm high. Which one is the correct statement?
1. The magnification is 4 and the image has been magnified.
2. The magnification is 4 and the image has been diminished.
3. The magnification is 0.25 and the image has been magnified.
4. The magnification is 0.25 and the image has been diminished.
Light travels through the air at 3 x 10^8 m/s. In a material it is found to travel at 2 x 10^8 m/s. The refractive index of the material is
1. 0.67
2. 1.0
3. 1.5
4. 2.0
A monochromatic ray of red light is shone onto a glass prism that has the section of an equilateral triangle. Which one of these statements correctly describes what would be seen
1. Nothing. The ray would have been absorbed.
2. Reflection, but the angle of incidence will be less than the angle of reflection.
3. The red ray will split into the colours of the rainbow
4. The red ray will be refracted and bend towards the normal as it passes into the glass. It will bend away from the normal as it comes out of the glass. The ray will still be red.
Which one of these statements is NOT true for a convex lens?
1. It is also called a converging lens
2. It has two principal foci.
3. It works by refraction.
4. It makes rays of light diverge.
Which one of these statements is NOT true for a diverging lens?
1. It is also called a concave lens.
2. The image can be real
3. The principal focus is virtual, only found by extending the diverging rays.
4. Diverging lenses are used to correct short sight.
When drawing ray diagrams for convex lenses, the image is found:
1. where the refracted ray and the undeviated ray meet
2. where the refracted ray and the undeviated ray meet the principal axis.
3. at the principal focus.
4. where the parallel ray meets the principal axis.
Which one of these statements is true about defects of vision and correcting them?
1. Long sight is when people cannot see distant objects clearly. It is corrected using a convex lens.
2. Long sight is when people cannot see close up objects clearly. It is corrected using a convex lens.
3. Long sight is when people cannot see distant objects clearly. It is corrected using a concave lens.
4. Long sight is when people cannot see close up objects clearly. It is corrected using a concave lens.
Which one of these statements best describes the image from a digital projector
1. It is virtual, upright, magnified
2. It is virtual, upright, diminished
3. It is real, inverted, magnified
4. It is real, upright, magnified
In a sound waves, there are regions of low pressure. These are called
1. refraction
2. rarefaction
3. refractory
4. refectory
Which one is correct description of a sound wave?
1. It is longitudinal and needs a material to travel in.
2. It is longitudinal and cannot travel in solids.
3. It is transverse and can travel through a vacuum.
4. It is transverse and needs a material to travel in.
Which one of these wave properties correctly applies to the pitch?
1. The amplitude
2. The direction of travel.
3. The frequency.
4. The shape of the wave
The sound level in the school library is measured at 35 decibels. The sound level in Mr Irvine's classroom is measured at 85 decibels. How much more intense is the sound level in Mr Irvine's classroom than in the library?
1. 0.41
2. 2.4
3. 50
4. 100 000
A musical note has a frequency of 250 Hz. Which one of these sets of data will be the correct sequence of harmonics of that note?
1. 62.5 Hz, 125 Hz, 500 Hz
2. 500 Hz, 750 Hz, 1000 Hz
3. 275 Hz, 300 Hz, 325 Hz
4. 300 Hz, 334 Hz, 446 Hz
Which one of these is NOT a use for ultrasound?
1. Taking pictures of a baby in its mother's womb
2. Detecting a flaw in a metal casting.
3. Cleaning delicate components
4. Detecting a leak in an underground pipe.
Ultrasound is the term for
1. sound waves which have too small an amplitude to be heard by most people.
2. low frequency sounds made by very large animals.
3. sounds that are above the range of human hearing
4. sounds that can travel in a vacuum.
Bats and dolphins use ultrasound for
1. echo location of their prey.
2. to detect whether the females are pregnant.
3. to call to each other over long distances.
4. RADAR
When an ultrasound probe is being used to look for a flaw in a casting, the pulses and echoes are displayed as spikes on a CRO screen. What pattern is the engineer most likely to see on the CRO screen when he picks up a flaw.
1. The pulse gives a small spike, and the echo is a big spike. The distance between them is the same as it was before.
2. The pulse gives a big spike, and the echo is a small spike. The distance between them is the same as it was before.
3. The pulse gives a big spike, and the echo is a small spike. The distance between them is less than it was before.
4. The echo spike disappears.
Sound travels at 1500 m/s in water. A ship sends out a pulse using its SONAR and receives an echo 4.5 seconds later. The depth of the sea at that point is:
1. 1350 m
2. 13500 m
3. 6750 m
4. 3375 m