PHYSICS
PAPER 1
TERM 2 OPENER EXAM
INSTRUCTIONS
- This paper consists of two sections; A and B
- Answer all the questions in section A and B
- All working must be clearly shown.
- Mathematical tables and electronic calculators may be used
- Candidates should answer the questions in English.
- Take g=10N/kg
SECTION A: 25mks (Answer all the questions)
- State one assumption made when determining the size of a molecule in an oil drop experiment (1 Mark)
- Air is blown into the horizontal tube as shown below.
- Indicate the levels of water in tubes A and B when air passes through the horizontal tube at a high velocity. (1 Mark)
- Explain your observation in (a) above (1 Mark)
- Sketch a velocity – time graph of a body moving with uniform velocity. (1 Mark)
- The figure below shows an empty wine glass.
- How is its stability affected when filled with wine? (1 Mark)
- Explain the observation in (a) above (1 Mark
- State one factor that affects heat transfer in solids. (1 Mark)
- The figure below shows a uniform bar of length 1 metre. Calculate the weight of the bar. (3 Marks)
- The figure below shows a u-tube containing the liquids X and Y. Given that the density of liquid X is 1.8g/cm3, calculate the density of liquid Y in g/cm3. (3 Marks)
- Name one factor that affects surface tension. (1 Mark)
- When a liquid is heated in a glass flask, its level first falls and then starts rising. Explain this observation. (2 Marks)
- The figure below shows two identical springs with negligible weight. The extension produced on the system is 10cm.
Determine the spring constant of each spring. (3 Marks) - A body A of mass 2kg moving with a velocity of 5m/s collides with a body B of mass 30kg travelling at 2m/s in the opposite direction. If the collision is perfectly inelastic, find their common velocity after collision. (3 Marks)
- The figure below shows a velocity time graph for a trolley
From the graph, calculate the distance covered by the trolley in the first 10 seconds (2 Marks) - State the reason why gases are easier to compress than solids. (1 Mark)
SECTION B: 55mks
-
- State the Hooke’s law (1 Mark)
- The table below shows the extension produced in a spring by various forces.
Extension (cm) 0 0.3 0.7 1.10 1.5 1.9 Force (N) 0 1.0 1.9 3.0 4.1 5.0 - Plot a graph of force against extension. (5 Marks)
- From the graph, determine the spring constant. (3 Marks)
- What force would cause an extension of 1.2cm on the spring? (2 Marks)
- The figure below shows a block and tackle system
- State the velocity ratio of the system (1 Mark)
- Mark the direction of tension in the strings (1 Mark)
- If an effort of 2N is applied, calculate the mechanical advantage of the system. (3 Marks)
- Calculate the efficiency of the system. (3 Marks)
- State why the efficiency of the system is less than 100%. (1 Mark)
- A body of mass 2kg is thrown vertically upwards with a velocity of 14m/s. Determine;
- The maximum height reached by the body (3 Marks)
- Its velocity after 0.5 seconds. (3 Marks)
- The time taken to reach maximum height. (3 Marks)
- Calculate the net force acting on the ball as it moves upwards if it experiences an air resistance of 8N. (2 Marks)
-
- State the Newton’s 2nd law of motion (1 Mark)
- A lady of mass 90kg is standing on the floor of a lift. Determine the reading on the weighing machine when
- Lift is at rest (2 Marks)
- Lift is moving upwards with an acceleration of 3m/s2 (2 Marks)
- Two masses of 4kg and 2kg are connected by a light string passing over a frictionless pulley as shown below.
Calculate the acceleration of the masses when left to move freely. (3 Marks) - A block of mass 35kg is pushed along a horizontal surface whose frictional force is 20N. If the force moving the block is 100N, calculate the co-efficient of friction between the block and the surface. (3 Marks)
- The figure below shows a hydraulic brake system.
A force of 20N is applied on the foot pedal connected to a piston of area 0.05m2. This causes a stopping force of 5000N on one wheel. Calculate.- Pressure in the master cylinder (3 Marks)
- Area of the slave piston. (3 Marks)
- Velocity ratio of the system. (3 Marks)
- Give two reasons why oil is used in the hydraulic brake system. (2 Marks)
- State two factors affecting pressure in liquids. (2 Marks)
MARKING SCHEME
SECTION A: 25mks (Answer all the questions)
- State one assumption made when determining the size of a molecule in an oil drop experiment
- The drop is perfectly spherical any one = ✔1 Mark
- The layers/ patch is one molecule thick.
- Air is blown into the horizontal tube as shown below.
- Indicate the levels of water in tubes A and B when air passes through the horizontal tube at a high velocity .
- Explain your observation in (a) above (1 Mark)
- In tube A, velocity of air above it is higher ✔than velocity of air above tube B
- Therefore in table A, pressure is lower than tube
- Indicate the levels of water in tubes A and B when air passes through the horizontal tube at a high velocity .
- Sketch a velocity – time graph of a body moving with uniform velocity. (1 Mark)
- The figure below shows an empty wire glass.
- How is its stability affected when filled with wine? (1 Mark
- Stability is reduced ✔
- Stability is reduced ✔
- Explain the observation in (a) above (1 Mark)
- The position of the centre of gravity is raised ✔1 when more weight is added on the upper side, reducing stability
- The position of the centre of gravity is raised ✔1 when more weight is added on the upper side, reducing stability
- How is its stability affected when filled with wine? (1 Mark
- State one factor that affects heat transfer in solids. (1 Mark)
- Length of the conductor
- Cross sectional area any one=✔1
- Temperature difference of the source
- Nature of the material making the conductor.
- The figure below shows a uniform bar of length 1 metre. Calculate the weight of the beam. (3 Marks)
Clockwise moments = Anti clockwise moments
0.1×W=0.4m×20N ✔ W=0.4×200.1✔
W=80N ✔ - The figure below shows a u-tube containing the liquids X and Y. Given that the density of liquid X is 1.8g/cm3, calculate the density of liquid Y in g/cm3. (3 Marks)
ρxhxg=ρxhxg ✔
ρxhx = ρxhx
1.8g/cm3 ×18cm=ρy×8cm ✔
ρy=1.8×188
ρy=4.05g/cm3 ✔ - Name one factor that affects surface tension. (1 Mark)
- Temperature
- Impurities
Any= ✔1
- When a liquid is heated in a glass flask, its level first falls and then starts rising. Explain this observation. (2 Marks
- The level first dropped due to expansion of glass ✔1
- The level then started rising when the heat reaches the water. ✔1
- The figure below shows two identical springs with negligible weight. The extension produced on the system is 10cm
Determine the spring constant of each spring. (3 Marks)- combined spring constant =k1+k2
for identical spring, ke=2k
f=2ke✔
30N=2k×0.1m✔
2k=30N/0.1m
2k=300N/m
k=150N/m ✔
- combined spring constant =k1+k2
- A body A of mass 2kg moving with a velocity of 5m/s collides with a body B of mass 30kg travelling at 2m/s in the opposite direction. If the collision is perfectly inelastic, find their common velocity after collision. (3 Marks)
- m1u1+ m2u2= (m1+m2)V✔
(2kg×5m/s )+(30kg×-2m/s )=(30kg+2kg)V ✔
10kgm/s -60kgm/s=32kgV
V=-1.56m/s
moves in the direction of 30kg body
- m1u1+ m2u2= (m1+m2)V✔
- The figure below shows a velocity time graph for a trolley
- From the graph, calculate the distance covered by the trolley in the first 10 seconds (2 Marks)
- Distance = Area under the graph from 0-10seconds
Area=(6+10/2)×25✔
8×25=200m
Distance = 200m ✔
- State the reason why gases are easier to compress than solids. (1 Mark)
- Gas particles have larger intermolecular distances than solids ✔
SECTION B: 55mks
-
- State Hook’s law (1 Mark)
- For a helical spring or any other elastic material, the extension is directly proportional to the stretching force, provided that elastic limit is not exceeded. ✔
- The table below shows the extension produced in a spring by various forces.
- Plot a graph of force against extension. (5 Marks)
- From the graph, determine the spring constant. (3 Marks)
- Gradient = Spring constant
K=5-21.85-0.75 ✔
K=31.1 ✔
K=2.73 N/cm - What force would cause an extension of 1.2cm on the spring? (2 Marks)
- Force = Ke
F = 2.73N/cm X 1.2cm✔
F = 3.276 N✔
- Gradient = Spring constant
- Plot a graph of force against extension. (5 Marks)
- State Hook’s law (1 Mark)
- The figure below shows a block tackle system
- State the velocity ratio of the system (1 Mark)
- 3 ✔
- Mark the direction of tension in the springs (1 Mark)
- All vertical tensions✔
- If an effort of 2N is applied, calculate the mechanical advantage of the system. (3 Marks)
MA=Load/Effort ✔
MA=4.5N2N ✔
MA=2.25 ✔ - Calculate the efficiency of the system. (3 Marks)
Efficiency=MAVR×100% ✔
2.25/3×100% ✔
Eff=75% - Explain why the efficiency of the system is less than 100%. (1 Mark)
- Weight of the pulley blocks/ dead weight ✔1
- Friction
- State the velocity ratio of the system (1 Mark)
- A body of mass 2kg is thrown vertically upwards with a velocity of 14m/s. Determine;
- The maximum height reached by the body (3 Marks)
V2=U2-2gh✔
V=0
U22gh
142=2×10×h✔
h=196/20
h=9.8m - Its velocity after 0.5 seconds. (3 Marks)
V=u-gt✔
V=14m/s-(10×0.55)
V=14-5
V=9m/s - The time taken to reach maximum height. (3 Marks)
- V=u-gt✔
O=14m/s-10t
10t=14✔
T=1410=1.4 seconds✔
- V=u-gt✔
- Calculate the net force acting on the ball as it moves upwards if it experiences an air resistance of 8N. (2 Marks)
Net force =mg-Air resistance
= (2kg×10N/kg)-8 N✔
=20N-8N
=12N✔
- The maximum height reached by the body (3 Marks)
-
- State the Newton’s 2nd law of motion (1 Mark)
- The rate of change of momentum of a body is directly proportional to the force applied and take place in the direction of the force ✔
- A lady of mass 90kg is standing on the floor of a lift. Determine the reading on the weighing machine when
- Lift is at rest (2 Marks)
At rest Reaction =mg
=90Kg ×10Nkg ✔
= 900N✔ - Lift is moving upwards with an acceleration of 3m/s2 (2 Marks)
R=mg+ma
=90×10+(90×3)✔
= 900N+270N
=1170N✔
- Lift is at rest (2 Marks)
- Two masses of 4kg and 2kg are connected by a light string passing over a frictionless pulley as shown below.
Calculate the acceleration of the masses when left to move freely. (3 Marks)- Net force=40N-20N=20N ✔
Force=Mass x acceleration
20N=6kga ✔
a=20N/6kg=3.33m/s2 ✔
- Net force=40N-20N=20N ✔
- A block of mass 35kg is pushed along a horizontal surface whose frictional force is 20N. If the force moving the block is 100N, calculate the co-efficient of friction between the block and the surface.
μ=F/R ✔
μ=20N/350N ✔
μ=0.06 ✔
- State the Newton’s 2nd law of motion (1 Mark)
- The figure below shows a hydraulic brake system.
A force of 20 N is applied on the foot pedal connected to a master piston of area 0.05m2. This causes a stopping force of 500N on one wheel. Calculate.- Pressure in the master cylinder (3 Marks)
- Pressure=force/area✔
=20N/0.05m2 ✔
Pressure=400N/m2 ✔
- Pressure=force/area✔
- Area of the slave piston. (3 Marks)
- Pressure is transmitted equally
400N/m2 =5000N/Area✔
Area=5000/400✔
Area=12.5m2✔
- Pressure is transmitted equally
- Velocity ratio of the system. (3 Marks)
V.R=Area of the load piston
Area of effort piston✔
V=R=12.5/0.05 ✔
=250 ✔ - Give two reasons why oil is used in the hydraulic brake system. (2 Marks)
- Incompressible ✔1
- Does not corrode the system ✔1
- State two factors affecting pressure in liquids. (2 Marks)
- Density
- Depth of the liquid Each = ✔1
- Pressure in the master cylinder (3 Marks)
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