Physics Paper 1 Questions and Answers - Kassu Jet Joint Mock Exams 2023

Instructions to Candidates

All working MUST be clearly shown.
Candidates should answer the questions in English
Take:
Acceleration due to gravity, g=10m/s²
Density of fresh water=1 g/cm³
Density of sea water=1.2 g/cm³

QUESTIONS

SECTION A (25 MARKS)

A vernier calliper has a zero error of 0.10 cm. Sketch the reading of the vernier calliper when used to measure the size of a test tube of internal diameter 2.60 cm. (1 mark)
An empty density bottle weighs 25g when empty and 70g when full of fresh water. Determine the volume of the density bottle. (2 marks)
The figure 1 below shows a flask filled with coloured water. The flask is fitted with a cork through which a tube is inserted. The flask is placed in crushed ice and allowed to cool.

State and explain the observation made. (2 marks)
The figure 2 below shows a straw with a hole in use to suck milk from a glass container.

State and explain the observation made upon sucking. (2 marks)
Two samples of bromine vapour are allowed to diffuse separately under different conditions, one in a vacuum and the other in air. It was observed that bromine diffused faster in vacuum than in air. Explain this observation. (1 mark)
The figure 3 below shows a graph of two containers having hot water and allowed to cool after sometime

Graph A represents temperature in container A and B temperature in container B. With reason identify the graph that represents a container with dull surface. (2 marks)
A student wanted to determine the mass of a stone using set up in figure 4 below.

Initially, the pointer was at X. On hanging 200g mass on the spring, the pointer moved to point Y. When he replaced the 200g mass with the stone, the pointer moved to point Z. Given that the elastic limit of the spring was not exceeded, determine the mass of the stone. (3 marks)
It is dangerous to stand near the edge of a platform in a railway station when a train passes without stopping. Explain. (1 mark)
Sketch a velocity – time graph for a body projected vertically upwards until it falls back to its point of projection. (2 marks)
Figure 5 below shows a uniform metre rule balanced on a knife edge.

Determine the weight of the metre rule. (3 marks)
State the S.I unit of work done by a stone mason in lifting a stone. (1 mark)
A certain mass of oxygen gas occupies a volume of 1.2 m³ at a pressure of 1.4 x 10⁵ Pa and temperature 15°C. Find its volume when the temperature is 0°c at a pressure of 1.1 x 10⁵ Pa. (3marks)
The figure 6 below shows a block floating in a liquid

When the liquid B is heated, it is observed that the block sinks further. Explain this observation. (2 marks)

SECTION B (55 MARKS)

1. A ball is thrown horizontally from the top of a vertical tower and strikes the ground
  at a point 60m from the bottom of the tower. Given that the height of the tower is
  50m, determine the;
  1. Time taken by the ball to hit the ground. (2 marks)
  2. Initial horizontal velocity of the ball. (2 marks)
  3. Vertical velocity of the ball just before striking the ground. (2 marks)
2. State one factor that affects centripetal force acting on a body. (1 mark)
3. A point on the rim of a wheel has a velocity of 5.6 m/s. If the rim has a radius of 0.4m, calculate;
  1. The angular velocity of the point. (2 marks)
  2. its centripetal acceleration. (2 marks)
4. State the reason why an object moving in a circular motion is said to be accelerating while the speed is constant. (1 mark)
1. A body of mass M₁ moving at velocity ‘u’ collides with another stationary body of mass M₂. Given that the two bodies coalesce after impact and move at a uniform velocity of V. Derive an expression for the final velocity of the bodies after the impact. (2 marks)
2. Given the following apparatus.
  - Empty density bottle of volume V
  - Liquid x
  - Beam balance
    Describe briefly how you can obtain the density of liquid X. (3 marks)
3. 1. Define terminal velocity. (1 mark)
  2. The figure 7 below shows a velocity time graph for a small sphere falling through water.
    On the same axes sketch the graph for the sphere when allowed to fall through glycerine. (1mark)
  3. Explain the difference in the graphs in (ii) above. (1 mark)
4. A liquid flows along a horizontal pipe of cross section area 24 cm2 with a speed of 3 m/s. The speed increases to 9 m/s where there is a constriction. Calculate the cross-section area of the constriction. (2 marks)
1. State the meaning of ‘specific latent heat of fusion”. (1 mark)
2. The figure 8 below shows a setup of apparatus used in an experiment to determine the specific latent heat of fusion of ice.
  1. On the diagram insert the ammeter and the voltmeter. (2 marks)
  2. From the experiment above, give the measureable quantities required to achieve the objective. (2 marks)
  3. The following readings were obtained after the heater was switched on for 10 minutes. (Mass of melted ice = 18g) Determine:
    1. Energy supplied by the 60W heater in the 10 minutes. (2 marks)
    2. Specific latent heat of fusion of ice. (3 marks)
  4. State any assumption in the experiment. (1 mark)
The diagram below shows the different parts of a wheel and axle machine.
1. 1. Indicate on the diagram the effort and load. (1 mark)
  2. Given that the handle wheel moved through a circular path of radius R and the axle moves through a circular path of radius r. Show that the velocity ratio of a wheel and axle is given by V.R = R/r. (2 marks)
2. In a wheel and axle, the wheel’s radius is 60cm, while the axle’s diameter is 24cm. the effort is 1.0N and the load is 4N. Work out:
  1. The velocity ratio. (2 marks)
  2. The mechanical advantage. (2 marks)
  3. The efficiency of the system. (2 marks)
1. A spherical buoy of diameter 0.6m and mass 50kg is connected to a rope tied to a sea bed so that ¾ of its volume is below the surface, as shown in the figure 9 below.
  1. On the diagram, indicate two forces acting on the buoy apart from weight, W. (2 marks)
  2. Determine:
    1. The weight of the buoy (1 mark)
    2. The upthrust on the buoy (2 marks)
    3. The tension, T, on the rope. (2 marks)
2. The figure 10 below shows a simple hydrometer.
  State the reason why;
  1. The upper stem is made narrow (1 mark)
  2. The lead shots are placed in the glass bulb. (1 mark)
3. The hydrometer above has a mass of 25g and allowed to float in oil of density 0.8g/cm³ with 6 cm of its stem above the oil. If the cross-sectional area of the stem is 0.5cm², find the length of its stem out of freshwater, if it is transferred and made to float in freshwater. (4 marks)

MARKING SCHEME

Instruments Reading = 2.6 +0.10 = 2.70cm
Mass of water = 70-25
= 45g
Density of water =1g/cm³
The figure 1 below shows a flask filled with coloured wate . he flask is fitted with a cork through which a tube is inserted. The flask is placed in crushed ice and allowed to cool.

Cork
Coloured Water
State and explain the observation made. (2 marks)
- The level of water in the tube rises slightly and then falls steadiy. The flask cools first, contracs and its volume reduces hence rise in the level of water. on cooling water, it contracts faster than glass thus a fall in its level
The figure 2 below shows a straw with a hole in use to suck milk from a glass container.

State and explain the observation made upon sucking. (2 marks)
- Milk does not rise up the straw. on sucking, air is pulled into the straw through the hole. This cause greater air pressure inside the sraw than atmpspheric pressure on surface of milk hence it does not rise.
Two samples of bromine vapour are allowed to diffuse separately under different conditions, one in a vacuum and the other in air. It was observed that bromine diffused faster in vacuum than in air. Explain this observation. (1 mark)
- diffuse separately under different observed that bromine diffused
  Cplllf.n n...P. .... a.c.G.cL«e o C Jac.(eaSÆa....G.mp.a1Æ..rur.f...
- in vacuum 1 Reduced
The figure 3 below shows a graph of two containers havin ot water and allowed to cool after sometime.

Graph A represents temperature in container A and B temperature in container B.
With reason identify the graph that represents a container with dull surface. (2 marks)
- B; dull surfaces are better emitters of radiant heat than shiny surfaces.
Initially, the pointer was at X. On hanging 200g mass on the spring, the pointer moved to point Y. When he replaced the 200g mass with the stone, the pointer moved to point Z. Given that the elastic limit of the spring was not exceeded, determine the mass of the stone. (3 marks)
- F=2N; e=0.40m
  F=ke
  2=k*0.4
  k=2/0.4
  =5N/m
- e₂=55-32=25cm
  F=ke
  =5*0.25
  =1.25N
  W=mg
  1.25=m*10
  m=0.125kg or 125g
It is dangerous to stand near the edge of a platform in a railway station when a train passes without stopping. Explain. (1 mark)
- The stream of air along the train is at higher velocity hence lower air pressure between the person and the train. the greater atmospheric pressure from the outer side pushes one towards the train.
Sketch a velocity — time graph for a body projected vertically upwards until it falls back to its point of projection.
10. Figure 5 below shows a uniform metre rule balanced on a knife edge.

Determine the weight of the metre rule. (3 marks)
- F₁d₁=f₂d₂
  (w*0.1)+(2*0.6)=4*0.4
  0.1W+1.2=1.6
  0.1W=1.6-1.2
  W=0.4/0.1
  =4N
State the S.I unit of work done by a stone mason in lifting a stone. (1 mark)
- Jouls or newtonmetre
A certain mass of oxygen gas occupies a volume of 1.2 m³ at a pressure of 1.4 x 10⁵ Pa and temperature 15°C. Find its volume when the temperature is 0°c at a pressure of 1.1 x 10⁵ Pa.
- _P1V₁/T₁ = P_2V₂/T₂
  1.4*10⁵*1.2/288 =1.1*10⁵*V/273
  V=1.4*10⁵*1.2*273/1.1*10⁵*288
  =1.448m³
The figure 6 below shows a block floating in a liquid.

When the liquid B is heated, it is observed that the block sinks further. Explain this observation.
- Volume of liquid increases upon heating hence density decreases, the black sinks more due to reduction n upthrust force acting on it.

SECTION B (55 MARKS

1. A ball is thrown horizontally from the top of a vertical tower and strikes the ground at a point 60m from the bottom of the tower. Given that the height of the tower is 50m, determine the;
  1. Time taken by the ball to hit the ground. (2 marks)
    h=1⁄2gt²
    50=1⁄2*10*t²
    50⁄5=5⁄5t²
    t²=10
    t=√10
    =3.162
  2. Initial horizontal velocity of the ball. (2 marks)
    R=ut
    60=u*3.162
    u=603.162
    =18.97m/s
  3. Vertical velocity of the ball just before striking the ground. (2 marks)
    V=U+gt
    =0+10*3.162
    =31.62m/s
2. State one factor that affects centripetal force acting on a body. (1 mark)
  - Angular velocity of the body
  - Radius of the path
  - Mass of the body
3. A point on the rim of a wheel has a velocity of 5.6 m/s. If the rim has a radius of 0.4m, calculate
  1. The angular velocity of the point. (2 marks)
    V=rW
    5.6=0.4*W
    W=5.6/0.4
    14 rad/s
  2. its centripetal acceleration. (2 marks)
    a=V²/r
    =5.6*5.6/0.4
    a=78.40m/s²
4. State the reason why an object moving in a circular motion is said to be accelerating while the speed is constant. (1 mark)
  - Instantaneous velocity change every time due to change in direction of motion.
1. A body of mass Ml moving at velocity 'u' collides with another stationary body of mass M2. Given that the two bodies coalesce after impact and move at a uniforrn velocity of V. Derive an expression for the final velocity of the bodies after the impact.
  - initial momentum of body 1=M₁U
    initial momentum of body 2=M₂*0=0
    final momentum after collision=(M₁M₂)
    since momentum is conserved
    M_1U+o=(M₁+M₂)
    V=M₁U/M₁+M₂
2. Given the following apparatus
  Empty density bottle of volume V
  Liquid x
  Beam balance
  1. Describe briefly how you can obtain the density of liquid X. (3 marks)
    Measure mass of empty density bottles as M₁. Fill the density bottle with liquid x, replace stopper and wipe the outside dry. Measure its mass with liquid x as M₂. Density of liquid x=M₂-M₁/V
3. 1. Define terminal velocity. (1 mark)
    Constant velocity attained by a body fallinf through a fluid when the sum of upthrust and viscons drag equals its weight.
  2. The figure 7 below shows a velocity time graph for a small sphere falling through water.
    On the same axes sketch the graph for the sphere when allowed to fall through glycerine. (1mark)
    
    On the same axes sketch the graph for the sphere when allowed to fall through glycerine. (1mark)
  3. Explain the difference in the graphs iii (ii) above.
    Glycerine being more dense than water has greater viscious drag or viscosity
4. A liquid flows along a horizontal pipe of cross section area 24 cm2 with a speed of 3 m/s. The speed increases to 9 m/s where there is a constriction. Calculate the cross-section area of the constriction. (2 marks)
  A₁V₁=A₂V₂
  24*3/9=9*A/9
  A=8cm²
1. State the meaning of 'specific latent heat of fusion". (1 mark)
  Quantity of heat energy required to change the stae of a unit mass of a substance from solid to liquid without change in temperature.
2. The figure 8 below shows a setup of apparatus used in an experiment to determine the specific latent heat of fusion of ice.
  1. On the diagram insert the ammeter and the voltmeter. (2 marks)
  2. From the experiment above, give the measureable quantities required to achieve the object.
    - Voltmeter reading
    - Ammeter reading
    - Mass of melted ice
    - Time using stopwatch
  3. The following readings were obtained after the heater was switched on for 10 minutes. (Mass of melted ice = 18g) Determine:
    1. Energy supplied by the 60W heater in the 10 minutes
      Q=PT
      =60*10*60
      =36000J
    2. Specific latent heat of fusion of ice.
      Q=mL_f
      3600/0.018=0.018/0.018l_f
      l_f=2.0*10⁶J/kg
  4. State any assumption in the experiment.
    No hea supplied by heater is lost to the surrounding
    Mass of ice melted due to room temperature is negligible
The diagram below shows the different parts of a wheel and axle machine.
1. 1. Indicate on the diagram the effort and load
  2. Given that the handle wheel moved through a circular path of radius R and the axle moves through a circular path of radius r. Show that the velocity ratio of a wheel and axle is given by V.R = R/r. (2 marks)
    V.R=distance covered by effort in one revolution/distance covered by load
    =2πR/2πr
    V.R=R⁄r
2. In a wheel and axle, the wheel’s radius is 60cm, while the axle’s diameter is 24cm. the effort is 1.0N and the load is 4N. Work out:
  1. The velocity raio
    V.R=R⁄r=60cm/12cm
    =5
  2. The mechanical advantage.
    M.A=l/E=4N/1N
    =4
  3. The efficiency of the system
    =M.A/V.R*100%
    4⁄5*100%
    =80%
1. A spherical buoy of diameter 0.6m and mass 50kg is connected to a rope tied to a sea bed so that ¾ of its volume is below the surface, as shown in the figure 9 below.
  1. on te diagram indicae two forces acting on he buoy apart from weight
  2. Determine:
    1. The weight of the buoy
      W=mg
      =50*10
      =500N
    2. The upthrust on the buoy
      U=jVg
      =1200*(4⁄3*3.142*0.3³)*3⁄4*10
      =1018N
    3. The tension, T, on the rope
      T=U-N
      =1018-500
      =518N
2. The figure 10 below shows a simple hydrometer
  
  State reason why;
  1. The upper stem is made narrow
    To improve sensitivity of the hydrometer
  2. The lead shots are placed in the glass bulb
    To enable the hydrometer to float upright
3. The hydrometer above has a mass of 25g and allowed to float in oil of density 0.8g/cm³ with 6 cm of its stem above the oil. If the cross-sectional area of the stem is 0.5cm², find the length of its stem out of freshwater, if it is transferred and made to float in freshwater. (4 marks)
  Vol.above oil =0.5*6=3cm³
  height =upthrust of oil on it
  25/1000*10=800*V*10
  vol.displaced=31.25cm³
  vol of hydrometer31.25+3=34.25cm³
  Again,
  weight=upthrust of water
  0.25=1000*V*10
  0.25/10000=10000V/10000
  V=25cm³
  vol above water=34.25-25=9.25cm³
  but V=A*L
  L=9.25/0.5
  =18.5