Physics Form 1 Questions and Answers - Term 3 Opener Exams 2021

Instructions

• Answer ALL the questions in the spaces provided
• Where necessary take:
  1. Earth’s gravitational intensity=10N/kg
  2. Density of water= 1000kg/m³
• Answer all the questions

QUESTIONS

1.  
   1. Define length                                                                 (1mk)
   2. Outline three steps that you should follow when measuring length using a metre rule  (3mks)
2.  
   1. What is a basic quantity?                                                (1mk)
   2. State two examples of a basic quantity and their SI units (2mks)
3. A plot of land is represented on a map by an area of 48.5cm2. If the scale on the map is 1:5000, determine the actual area of the land in square metres                           (3mks)
4. When a narrow tube is dipped in a beaker containing water, the water rises up the tube.
   1. What is the name given to this effect?                           (1mk)
   2. Explain the observation                                                (1mk)
5. State the two factors affecting the surface tension of a liquid.    (2mks)
6. The atmospheric pressure at a place was measured as 740mm of mercury. Calculate the pressure at the place in Pascals. (density of mercury is 13.6g/cm³)             (3mks)
7. Explain how a drinking straw works when used to drink a liquid.               (2mks)
8. State the kinetic theory of matter.                          (1mk)
9.  
   1. In the smoke cell experiment, the smoke is observed to be in a random motion. Explain the cause of the motion                                                             (1mk)
   2. State and explain the effect on the motion when the temperature of the smoke cell is increased   (2mks)
10.  
    1. What is diffusion?                                                 (1mk)
    2. State the factors affecting the rate of diffusion of a gas                   (2mks)
11. State any three differences between mass and weight                                   (3mks)
12. An object has a mass of 120g.what is the weight of the object at the moon surface? (gravitational intensity of the moon is a third that of the earth)                     (2mks)
13. The water level in a burette is 40.6cm³. 50 drops of water each of volume 0.2cm³are added to the water in the burette. What is the final reading of the burette?     (3mks)
14. On the axis provided, sketch a graph of volume against temperature of water from 0º to 20ºC.   (2mks)
    
15. It is easier to detect a bad smell from a gaseous substance than a solid substance. Explain  (1mk)
16.  
    1. Define pressure           (1 mark)
    2.  
       1. State Pascal’s principal. (1 mark)
       2. The figure below represents a section of a hydraulic machine. The area of Pistons A and B are 0.03m² and 0.5m respectively. A force of 60N is applied on the piston.
          
          Determine the:
          1. Pressure exerted on oil by piston A                              (2mks)
          2. Maximum force that can be lifted by the system            (2mks)
       3. Give two reasons why oil and NOT water is selected for use in the system in (ii) above  (2mks)
17. The figure below shows a circuit diagram of a device for controlling the temperature in a room.
    
    
    1. Explain the purpose of the bimetallic strip.                                        (2 marks)
    2. Describe how the circuit controls the temperature when the switch is closed.  (3 marks)
18.  
    1. The figure below shows two identical copper plates one painted black and the other is white. The corks are stuck to the plates using some wax and a Bunsen flame is placed equidistant from the two plates.
       
       Which cork is likely to fall off first from the plate? Give reason for your answer   (2mks)
    2. The figure below shows a paddle wheel placed in a beaker containing water. When the water is heated at the point indicated, the wheel rotates.
       
       
       1. Explain why the wheel rotates                                            (2mks)
       2. State the direction in which it rotates                                    (1mk)
    3. A vacuum flask is designed to keep a liquid hot for a long time. Explain how heat losses are reduced in a vacuum flask                               (3mks)
19.  
    1. Define density                                                                     (1mk)
    2. A solid block measures 25cm by10cm by 8cm. if the block has a mass of 3.2kg, calculate:
       1. The volume of the block                                        (2mks)
       2. The density of the block expressed in SI units         (3mks)
    3. The mass of an empty density bottle together with its stopper is 24.8g. The bottle weighs 49.8g when filled with water. When the bottle is emptied and filled with another liquid, it weighs 48.8g. Determine the density of the liquid.                                         (3mks)
20.  
    1. What is a thermometric liquid?                                               (1mk)
    2. State any three qualities of a good thermometric liquid            (3mks)
    3. Give any two advantages that mercury has over alcohol as a thermometric liquid (2mks)
    4. Explain how each of the following can be increased in a liquid-in-glass thermometer:
       1. Sensitivity (1mk)
       2. Accuracy (1mk)
21.  
    1. State the laws of reflection                             (2mks)
    2. Two plane mirrors are inclined at an angle of   60º. How many images do the mirrors form?  (2mks)
    3. State one application of a plane mirror                   (1mk)

MARKING SCHEME

1.  
   1. Is the measure of the distance between two points
   2.  
      • Place the metre rule in contact with the object being measured
      • Align the zero mark with one end of object
      • With eye directly above the other end read the mark coinciding with this end
2.  
   1. A quantity whose value cannot be determined from other quantities
   2.  
      • Mass-kilogram
      • Length-metre
      • Time-second
      • Temperature-Kelvin
      • Electric current-Ampere
      • Luminous intensity-Candela
      • Amount of substance-mole   (Any two)
3. Area of a square on map represents:
   5000 x 5000=25000000cm² on actual ground
   =2500m2
   Actual area =2500 x 48.5
   =121250m²
4.  
   1. Capillarity
   2. The adhesive between the glass and water molecules is greater than the cohesive force in water hence the water rises up the tube.
5.  
   • Temperature
   • Presence of impurity
6.   
   
7. A person sucks on the upper end of straw, the pressure inside the straw reduces, atmospheric pressure acting on the liquid surface forces liquid up through the lower end
8. Matter is made up of small particles that are in a continuous random motion
9.  
   1. The smoke particles are in collision with unseen air particles which are in a continuous random motion
   2. The motion increases.
      • Increase in temperature increases the kinetic energy of the particles hence increasing the motion
10.  
    1. The movement of particles from a region of high concentration towards a region of low concentration
    2.  
       • Temperature
       • Density
11.  
    

    Mass	Weight
    Quantity of matter in a body	Gravitational pull on an object
    Measured using beam balance	Measured using spring balance
    SI unit is the kilogram	SI unit is the Newton
    Constant everywhere	Varies
    Scalar quantity	Vector quantity

12.  
    
13.  
    • Added volume = 50 x 0.2 = 10cm³
    • New volume = 40.6-10 = 30.6cm³ 
14.  
    
    
15. Gases diffuse faster than solids
16.  
    1. Is the force acting perpendicularly per unit area
    2.  
       1. An enclosed fluid transmits pressure equally in all directions
       2.  
          1. Pressure exerted on oil by piston A                               (2mks)
             
                   
          2. Maximum force that can be lifted by the system         (2mks)
             
             
       3.  
          • Oil lubricates the system
          • Oil is does not rust or corrode the machine
17.  
    1. It makes or breaks (closes or opens) the circuit hence maintaining the temperature at the set value.
    2. When the switch is closed, current flows in the circuit and the heating element becomes hot. As temperature increases the bimetallic strip expands and curves outwards hence opening circuit. As temperature falls the bimetallic strip contracts and contacts close. The process is repeated.
18.  
    1.  
       • The cork on the black plate.
       • Black surfaces absorb heat more than white surfaces
    2.  
       1. When the water is heated it expands, becomes less dense and rises. As cool water moves down to replace it convection currents are set up causing the wheel to rotate.
       2. Anticlockwise
    3.  
       • Vacuum – reduces heat loss by convection and conduction
       • Double silvered walls – reduces radiation
       • Rubber cork – reduces conduction and evaporation
19.  
    1. density is the mass per unit volume of a substance
    2.  
       1. A solid block measures 25cm by10cm by 8cm. if the block has a mass of 3.2kg, calculate:
          V = l x w x h
          = 25 x 10 x 8
          = 2000cm³
       2.  
          
    3.  
       Mass of water = 49.8-24.8 = 25g
       Mass of liquid = 48.8-24.8 = 24g
       Volume of bottle = volume of water = 25cm³
       Density of liquid = 
       = 0.96cm³
20.  
    1. A liquid suitable for use in a thermometer
    2.  
       • Good conductor of heat
       • Expand uniformly
       • Wide temperature range
       • Opaque
       • Does not wet glass
    3.  
       • Mercury is: Opaque
       • Good conductor of heat
       • Does not wet glass
       • Has a high boiling point
    4.  
       1. By using a thin walled bulb
       2. By using a narrow bore
21.  
    1.  
       • The incident ray, the normal and the reflected ray all lie on the same plane
       • The angle of incidence is equal to angle of reflection
    2.    
       
    3. Dressing mirrors, kaleidoscope, mirror periscope