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  1. C

    forces and motion problem

    A solid sphere of radius 0.05 m and mass 1.00 kg rolls on a horizontal surface with a vlocity of 15 ms-1 and then rolls up an incline at an angle of 20o.If friction forces equal zero, to what height above the horizontal surface will the sphere rise before it comes to rest? (the moment of...
  2. C

    potential/ kenitic energy problem

    How much work is done to increase the angular velocity of a wheel from rest to a final value of 20 radians per second.The wheel has a moment of inertia of 0.30 kg m2 .What torque is required to reach this angular velocity in a time of 5.0 s?
  3. C

    moments of inertia

    A solid sphere of radius 0.05 m and mass 1.00 kg rolls on a horizontal surface with a velocity of 15 ms-1 and then rolls up an incline at an angle of 20o.If friction forces can be neglected , to what height above the horizontal surface will the sphere rise before it comes to rest? (the moment...
  4. C

    help with motion problemz

    A ball of mass 0.25 kg moving horizontally with a velocity of 13 ms-1 is hit with a bat. The final velocity of the ball is 19 ms-1 in the opposite direction. If the bat is in contact with the ball for 0.02 s, find the average force of the bat on the ball.
  5. C

    please help with question on forces and motion

    A car goes round a circular track of radius 30.0 m which is banked at an angle of 15o to the horizontal to make it safer when there is ice on the road. What is the maximum safe speed of the car if there is no friction between the tyres and the road?
  7. C

    newtons lawz problem need help

    A plastic block slides from rest a distance of 0.70 m down a plank. If there is no friction between the block and the plank which is at an angle of 20o to the horizontal, calculate the velocity of the block when it has reached the bottom of the plank.
  8. C

    oxidation reduction problem important

    2H202 ----> 2H20 + 02 which species is the oxidising agent/ reducing agent and why ? please help thanx
  9. C

    percentage compositions

    a sample of impure Ba(NO3)2 is analysed by dissolving 0.222g of the mixture completely in water. excess Na2SO4 solution is added and a precipitate of BaSO4 is formed. the mass of the precipitate, after filtering and drying, is 0.182g . calculate the percent of purity of the original Ba(NO3)2...
  10. C

    a typical questions of gases

    a sample of CO gas was collected over water at 20 degrees and a total pressure of 1.045 atm. if the volume of water collected was 50.0 ml, what was the mass of CO collected ? (at 20 degrees the vapour pressure of water is 17.5 torr. )
  11. C

    help with frictional forces

    how do i caluclate the coefficient of friction force: i noe F (friction) = coefficent of friction x F (normal) A block of mass 3.00kg is being pushed across a rough surface with a velocity of 5.0 ms-1 When the pushing force is removed the block comes to rest in a distance of 3.0 m...
  13. C

    important vector problem

    A and B are two vectors. A= (5i+3j) and B= (3i-2j). ( i) Calculate the magnitude and direction of the vectors A and B. (ii) Calculate the magnitude and direction of the sum A +B. (iii) Find the scalar product A.B for these two vectors. (iv) Find the angle between vector A and B.
  14. C

    uniform circular motion problem

    Through how many radians does a point on the surface of the earth move in 6 hours? What is the speed of a point on the earth's equater? (radius of the earth is 6370km.)
  15. C

    motors

    A flywheel rotates at 480 rpm. Calculate a) the angular speed at any point on the wheel and b) the tangential speed 30.0cm from the centre
  16. C

    harder applicxation of newtons law

    A block of mass 3.00kg is being pushed across a rough surface with a velocity of 5.0 ms-1 When the pushing force is removed the block comes to rest in a distance of 3.0 m. Calculate the coefficient of friction between the block and the rough surface.
  17. C

    important: hard hsc style question on motion

    veronica angrily throws her engagement ring staight up from the roof of a building, 12m above the ground, with an initial speed of 6.00m/s neglecting air resistance, for the motion from her hand to the ground, what are the magnitude and direction of (a) the average velocity of the ring...
  19. C

    oxidation numbers problem

    what is the oxidation number of Bi in NaBiO3
  20. C

    important : selective school half yearly question

    the compound cumene contains only carbon and hydrogen. combustion of 71.5 g of cumene produces 235.6 g of CO2 and 64.3g of H2O. what is its molecular formula?
  21. C

    important: past hSC question not many ppl got it right

    an element X forms both a monoxide (XO) and a dioxide (XO2). conversion of 10.00g of X0 to XO2 produces 15.33g of the dioxide. what is therelative atomic mass of X?
  22. C

    important : mass - mass calculations past hsc question

    when lead oxide is heated with carbon, metallic lead is formed. 2PbO (s) + C (s) ------> 2Pb (s) + CO2 (g) if 87.3g of lead oxide were mixeed with 2.62g of charcoal (carbon), what mass of metallic lead would be formed ?
  23. C

    molar mass problem important for hsc

    can any1 help .... what is the relative molar mass of C12 H22 011 to 2 decimal places with units ? the answer i get is 342.30 amu but is wrong
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