Forces and Motion
A car accelerates uniformly from rest to 30 m/s in 5 seconds. Calculate its acceleration
6
A roller coaster car of mass 500 kg is at the top of a 20 m hill. Calculate its gravitational potential energy.
98000 J
What is the formula that relates speed of light and refractive index?
n = v (in vacuum) / v (in medium)
A wire carries a current of 3 A for 10 seconds. How much charge flows through the wire?
Why does evaporation cause cooling?
Faster-moving particles escape, lowering the average kinetic energy of the remaining particles.
A 2 kg object is dropped from a height of 10 m. Ignore air resistance. Calculate the impact velocity just before it hits the ground.
14 m/s
A 120 W motor lifts a 10 kg object vertically at a steady speed. What is the maximum height it can lift the object in 5 seconds?
6.12 m
A light ray in water (n=1.33n = 1.33n=1.33) enters the air at an angle of 30°. Calculate the angle of refraction.
41
State two advantages of alternating current (AC) over direct current (DC).
AC can be transmitted over long distances with less power loss; AC voltage can be easily changed using transformers.
The pressure of a gas doubles when its volume halves at constant temperature. Which law explains this?
bouyant, gravitational
A carpenter attempts to loosen a bolt that has rusted. To turn the bolt, they exert a force of 22 N using a spanner of length 20 cm. The force is exerted 5 cm from the end of the spanner.
Calculate the turning effect of the force.
3.3 Nm
What is the difference between longitudinal and transverse wave?
Longitudinal waves travel paralled to vibration of particles
Transverse waves travel prependicular to vibration of particles
What is the output voltage when the Np = 80, Ns = 400, and Vp =48 V?
240 V
How do we stop alpha, beta, and gamma rays?
alpha - thin paper
beta - 2-3 cm Al sheet
gamma - 7 cm lead /concrete
How can we reduce friction? Name 3 ways.
polish surface
use lubricant/oil
use wheels
A parent and child are at opposite ends of a playground see-saw.
The weight force acting on the parent is 690 N and the weight force acting on the child is 140 N.
The adult sits at a distance of 0.3 m from the pivot.
Calculate the distance the child must sit from the pivot for the see-saw to be balanced.
Use the principle of moments in your calculation.
1.5 m from pivot
Describe total internal reflection and state the condition for it to occur
light travels from a denser to a less dense medium at an angle greater than the critical angle
What will happen to the pointer on the voltmeter when the magnet is stationary in the centre of the coil?
There will be no deflection of the needle
Define half-life.
The time taken for half the radioactive nuclei in a sample to decay.
OR
The time taken for original activity to reduce by half
Which shows the free body diagram of a concert-goer sitting on a hill, enjoying the show?
5
A 2.5 kg ball moving at 5 m/s collides with a 2.5 kg stationary ball in a perfectly elastic collision. What is the velocity of the second ball after the collision?
5m/s
Draw and label the complete ray diagram of a light wave traveling 30 degree from the surface from air into glass. Show how you would calculate the refractive index,n.
When moving a wire through a magnetic field, the direction of the induced emf can be determined using?
FRHR (right hand dynamo rule)
In a fusion reaction, two hydrogen nuclei form helium. Why is it difficult to achieve this on Earth?
High temperature and pressure are required to overcome electrostatic repulsion.