KNEC KCSE Physics Paper 1 – 2014 Nakuru District Mock

Two micrometers screw gauges were used to measure the diameter of a wire. The readings
obtained were 2.06mm and 2.08mm respectively. State two possible causes of the difference
in the readings.

Two steel wires of diameter 0.30mm and 0.50mm are rolled into springs of equal number of
turns and length. On the axes below, sketch their graphs of force against extension.(2mks)

(ii) Give a reason for any difference between the graphs. (1mk)

1,500cm³ of wine is mixed with 1,000cm³ of water. Given that the density of mixture is
880kg/m³ and that of water is 1000kg/m³, find the density of the wine.

Figure 1 shows two liquids A and B connected to a low pressure cylinder. When the tap is
opened, the liquids take their levels as shown. Given that the density of liquid A is 1.2g/cm³. Determine the density of liquid B.

Some smoke was enclosed in a smoke cell and observed under a microscope as shown in
figure 2. State and explain the observed motion of the smoke particles.

In vacuum flasks, double walled-glass with a vacuum between the walls is most commonly
used in the basic design. State the role of the ,
i. Vacuum (1mk)
ii. The silver on the wall (1mk)

A uniform meter rule is balanced by a set of forces as shown in figure 3 below. A force of 8N
is suspended at a point X.

Determine the value of X.

Figure 4 below shows test-tube containing water at 0^oC and suspended using a string.
State what would be observed if the temperature drops to -10^o C.

A spring of length 10cm is stretched to 14cm when loaded with a mass of 400g. Determine
its length when loaded with a mass of 700g.

State Bernoulli’s’ principle.

Figure 5. Shows a block of metal resting on an inclined plank of wood. Indicate any two
forces that are in action.

(a) State the law of floatation. (1mk)
(b) A simple hydrometer is made using a test-tube that is partially filled with lead
shots. The hydrometer is made to float in water and the level of the water marked
on the side of test-tube. Describe how the test-tube can be calibrated to measure
relative density. (2mk)
(c) A cork of mass 1000g is held floating in water by means of a spherical steel ball
as shown

(i) Given that the mass of the sphere is 500g and volume 70cm³. The base area of cork
is 25cm². Determine the total upthrust. (2mk)

(ii) The string accidentally cuts. Find the new depth of the cork. (3mk)
(iii) Determine the initial acceleration of the steel ball. (3mk)
(iv) State why after sometime, the acceleration would be lower than the value obtained
(1mk)

(a) State Newton’s second law of motion (1mk)
(b) A bullet of mass 50g is fired from a gun at muzzle velocity of 400m/s.
Given that the gun has a mass of 5kg, find the recoil velocity of the gun. (3mks)

(c) A box of mass 5kg is at rest on an incline plane at a distance of 10m from the base
as show in figure 6 below.

(i) Determine the friction force present on the incline as a result of the mass. (3mks)
(ii) An oil leakage from inside the box dripped on the inclined plane. After sometimes, it was
noted that the box slide down the incline plane. Determine the acceleration of the box
just before it landed at the base. (3mk)

(iii) Calculate the velocity of the block at time of landing at the base (3mk)

(a) Define the term centripetal acceleration. (1mk)
(b) A pendulum bob of mass 2kg is suspended by a string of length 5m as shown in
figure 7 below.

Determine;
(i) The speed of the bob when the ball passes point X. (2mks)
(ii) The force on the string when the bob passes at the point X. (3mk)
(c) Figure 8 shows a turn table of radius 4m with a mass fixed to its centre by means
of a spring balance. The mass is made to rotate with a varying angular velocity. The
tension on the string was measured for various values of angular velocity. The table
shows the results obtained.

(i) Plot a graph of T against ω². (5mk)
(ii) From the graph, determine the mass of the bob given that T=mω²r – c, where c is
a constant (3mk)

(a) Explain the term ‘absolute zero’. (1mk)
(b) Using the kinetic theory of gases, explain how reduction in volume of a fixed
mass of gas leads increase in temperature (2mk)
(c) Figure10. Below shows a set-up used to verify a certain gas law.

(i) State one physical factor that shall remain constant (1mk)
(ii) State what shall be varied for one to obtain results. (1mk)

(iii) Explain how the apparatus shall be used to verify the intended law. (4mk)
Identify one limitation of the set up in the experiment. (1mk)

(a) Define efficiency as applied to simple machines (1mk)
(b) Figure 11below represents the hydraulic brake of a machine. Piston X has a
diameter of 20cm while Y has a diameter of 2cm.
(i) A force of 20N is required at Y to stop the machine. Determine the braking force
(2mk)

(ii) State one reason why oil is preferred to water for use in the brake system(1mk)
iii) State the principle that the hydraulic brake above is based on (1mk)
iv) State with a reason what would be observed on the machine if piston X was replaced
by one of a smaller cross-sectional area. (1mk)