Category: A-level physics
UACE physics paper 2 2019 marking guide (A-level)
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Moment of a force
Moment of force is the product of the force and perpendicular distance from the point to the point of action of the force. Please Subscribe ... Read More
State Archimedes’ principle.
Archimedes’ Principle state that when a body is wholly or partially immersed in a fluid, it experiences an up thrust equal to the weight of ... Read More
Explain why velocity of a liquid at a wide part of a tube is less than that at a narrow part.
Volume flow per second is constant, so by the equation of continuity AV = constant’, the velocity is inversely proportional to cross section area. ... Read More
Explain the effect of temperature on viscosity of a liquid.
Increase in temperature of a liquid increases the separation between the molecules and reduce the intermolecular attraction leading to a decrease in viscosity. Please ... Read More
Show that the pressure, P, exerted at a depth, h, below the free surface of a liquid of density, ρ, is given by P =hρg.
Banking of roads is defined as the phenomenon in which the edges are raised for the curved roads above the inner edge to provide the necessary ... Read More
Explain the effect of increase in temperature on viscosity of a liquid.
When temperature rises, the molecular separation of liquid molecules increases and the intermolecular forces decrease. The resistance to flow then decreases hence a decrease in ... Read More
What is meant by the following terms, steady flow and viscosity?
Steady flow is the flow where the velocity of the liquid past any given point is constant. Viscosity is the friction between layers of a ... Read More
Derive an expression for maximum horizontal distance travelled by a projectile in terms of the initial speed, u, and the angle of projection, θ, to the horizontal.
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Explain A cosmonaut in a satellite which is in a free circular orbit around the earth experiences the sensation of weightlessness even though there is influence of gravitational field on earth.
The sensation of weight is caused by the reaction of the floor on a person. In orbit, the cosmonaut and the floor have the ... Read More
Describe an experiment to determine the acceleration due to gravity, g, using a spiral spring, of known constant.
Clamp the spring on a retort stand Fix a horizontal pin at free end of the spring to act as a pointer. Place a ... Read More
State four characteristics of simple harmonic motion.
A periodic motion Acceleration is proportional to displacement Acceleration is directed towards a fixed point Mechanical energy is conserved. Please Subscribe to promote this website. ... Read More
Explain the energy changes which occur when a pendulum is set into motion.
Potential energy at A → Kinetic + potential energy at B → kinetic at C → Kinetic + potential energy at D→ potential energy at ... Read More
Define uniformly accelerated motion
Uniformly accelerated motion is where velocity changes by the same amount in the same time interval Please Subscribe to promote this website. Subscription is free ... Read More
Explain why a person standing near a railway line is sucked towards the railway line when a fast moving train passes.
Between the man and the train, the velocity of air is increased due to the motion of the train resulting in a decrease in pressure ... Read More
Describe an experiment to measure the coefficient of viscosity of water using Ponselle’s formula.
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Explain laminar flow and turbulent flow.
Laminar flow is the type of flow where equidistant layers of fluid from the axis of flow have the same velocity flow line are parallel ... Read More
Define terminal velocity
Terminal velocity is the maximum velocity attained by a body falling through a viscous fluid. Please Subscribe to promote this website. Subscription is free Share ... Read More
Describe, stating the necessary precautions an experiment to measure the coefficient of viscosity of a liquid using Stroke’s law.
A liquid of known density, ρ, is put in a tall transparent glass with reference marks A and B, h metres apart A spherical solid ... Read More
Explain the origin of viscosity in air and account for the effect of temperature on it.
In air, molecules are further apart and have negligible intermolecular forces. Therefore the molecules move randomly colliding with one another and continuously transferring momentum to ... Read More
Define coefficient of viscosity and state its units.
Coefficient of viscosity is the frictional force on unit area of a liquid in a region of unit velocity gradient. Units Pas or Nsm-2 ... Read More
What is projectile motion?
Projectile motion is motion of the body which after being given an initial velocity moves under the influence of gravity. Please Subscribe to promote this ... Read More
Explain briefly what is meant by internal energy of a substance.
The internal energy of a body or a substance is the total sum of kinetic energy and potential energy of the particles of a substance ... Read More
Prove the work-energy theorem for a body moving with constant acceleration.
Therefore work done = change in kinetic energy Please Subscribe to promote this website. Subscription is free Share with a friend Your comment is valuable ... Read More
State work-energy theorem.
Work-energy theorem states that work done by the net force acting on a body is equal to the change in its kinetic energy. Please Subscribe ... Read More
Explain whether a person carrying a bucket of water does any work on the bucket while walking on a levelled road.
Explain whether a person carrying a bucket of water does any work on the bucket while walking on a levelled road. There is no net ... Read More
Define work and energy
Work is a product of force and distance moved in the direction of force. Energy is the ability to do work Please Subscribe to promote ... Read More
State Hooke’s law
Hooke’s law states that the extension of a material is proportional to the stretching force provided the elastic limit is not exceeded. Please ... Read More
Explain why passengers in a bus are thrown backwards when the bus suddenly start moving
Passengers are thrown backwards because of inertia. When the bus sets off the passenger tend to stay at rest because the force acts on the ... Read More
Explain how a rocket is kept in motion.
Fuel is burst in a combustion chamber and exhaust gases are expelled at high velocity. This causes a large backward momentum. From the principle of ... Read More
Explain how wind at a high speed over the roof of a building can cause the roof to be ripped off the building.
Explain how wind at a high speed over the roof of a building can cause the roof to be ripped off the building. Wind blowing ... Read More
State Bernoulli’s principle
State Bernoulli’s principle Bernoulli’s Principle states that for a streamline motion of an incompressible non viscous fluid, the sum of pressure at any point and ... Read More
Explain why water dripping out of a tap does so in spherical shapes.
For any given volume, a sphere is a shape that offer minimum surface area and therefore the most stable Please Subscribe to promote this website. ... Read More
Show the surface energy and surface tension are numerically equal.
F a wire frame ABCD is put in a solution of surface tension γ and a film of the solution forms on ABCD; and if ... Read More
Distinguish between surface tension and surface energy
Surface tension is a force per unit length acting at right angle to one side of an imaginary line drawn in the liquid surface Surface ... Read More
Describe laboratory method of determining the universal gravitational constant, G.
Determining gravitational constant Two equal lead spheres A and B each of mass, m, are attached to end of a bar AB of length, L. ... Read More
Derive an expression for the period, T, of a satellite in a circular orbit of radius, r, above the earth in terms of mass of earth, m, gravitational constant, G and r.
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what is a parking orbit of a satellite?
A parking orbit of a satellite is the path in space followed by a satellite whose period of revolution is equal to the period of ... Read More
Explain why a piece of rubber stretches much more than a metal wire of the same length and cross section
Rubber consist of coiled molecules while metal does not. When load is applied to rubber, the molecules uncoil leading to a larger extension Please Subscribe ... Read More
Explain the precautions taken in determinations of Young’s modulus of a wire.
After each reading, the load is removed to check that the wire returns to its original length, to ensure that elastic limit is not exceeded. ... Read More
Define Young’s modulus.
Young’s modulus is the ratio of tensile stress to tensile strain Please Subscribe to promote this website. Subscription is free Share with a friend ... Read More
State disadvantages of friction.
State disadvantages of friction. Wastes energy Causes wear and tear Causes noise Generates unnecessary heat Please Subscribe to promote this website. Subscription is free ... Read More
Describe an experiment to measure the coefficient of static friction.
A block of mass m is placed on a flat table and connected to a scale pan as shown in the diagram above. Small weights ... Read More
Show that Newton’s law of gravitation is consistent with Kepler’s third law.
Consider a planet of mass MP moving around the sun of mass MS in a circular orbit of radius r. Please Subscribe to promote this ... Read More
State Newton’s law of gravitation
Newton’s law of gravitation states that every particle of matter attracts every other particle with a force which is directly proportional to the product of ... Read More
Forced oscillations
Forced oscillations Force oscillations are those which are maintained by external force. Please Subscribe to promote this website. Subscription is free Share with a ... Read More
What is damped oscillations
damped oscillations Damped oscillation are oscillations in which the oscillatory system loses energy to the surroundings due to dissipative forces. The amplitude of the oscillations ... Read More
What is meant by conservative forces?
A conservative force is one for which the work done to move a body from one point to another is independent of the path taken ... Read More
Briefly explain the three states of equilibrium
When a body in stable equilibrium is slightly displaced, its centre of gravity is raised. When released, it returns to its original position. When ... Read More
State the conditions for a body to be in equilibrium under action of coplanar forces.
Conditions for equilibrium Resultant force on the body is zero Algebraic sum of moments at any point is zero. Please Subscribe to promote this ... Read More
Explain why a body placed on a rough plane will slide when the angle of inclination is increased.
A body of mass, m placed on a plane inclined at an angle θ above the horizontal has its component mgsinθ downwards along the plane. ... Read More
Define inertia.
Inertial is the reluctance of a body to start moving once at rest or to stop moving once it has begun to move. Please Subscribe ... Read More
What is an impulse in physics
Impulse is a product of force and time of action of the force Please Subscribe to promote this website. Subscription is free Share with a ... Read More
What is meant by efficiency of a machine?
Efficiency is the ratio of useful work done by a machine to the energy used by the machine; (expressed as percentage) Please Subscribe to promote ... Read More
Explain why tyres of a vehicle travelling on a hard surfaced road may burst
When the car moves on a hard surface, friction between the tyres and the surface causes heating and the temperature inside the tyres increase. The ... Read More
Describe an experiment to determine Young’s Modulus of a steel wire.
Experiment to determine Young’s Modulus for a metal wire Two thin, long wires of the same material and length P and Q are suspended from ... Read More
Define elastic limit of a material.
Elastic limit is the maximum load which a material can experience and still regain its original size and shape once the load has been removed. ... Read More
Define dimensions of a physical quantity.
Dimensions of a physical quantity is the way it is related to fundamental quantities; mass, length and time Please Subscribe to promote this ... Read More
State the effect of temperature on surface tension of a liquid.
Increase in temperature lowers surface tension Please Subscribe to promote this website. Subscription is free Share with a friend Your comment is valuable ... Read More
Explain what is meant by work hardening.
Work hardening is the strengthening of a material by repeatedly deforming it. Atomic planes slide over each other, this increases plane dislocations which prevent ... Read More