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What effect does MnO2 have on the reaction rate of the decomposition of hydrogen peroxide?
What effect does MnO2 have on the equilibrium constant?
A single cylinder four stroke internal combustion engine develops 30 kW at 300 rev/min. The
turning-moment diagram for the expansion and compression strokes may be taken as two isosceles
triangles, on bases 0 to π and 3π to 4π radians respectively, and the net work done during the
exhaust and inlet strokes is zero. The work done during compression is negative and is one quarter
of that during expansion. Sketch the turning moment diagram for one cycle and find the maximum
value of the turning moment during expansion. If the load remains constant, mark on the diagram
the points of maximum and minimum speed. Also find the moment of inertia, in kg m 2
, of a flywheel
to keep the speed fluctuation within ±1.5 per cent of the mean speed.
. A machine press is worked by an electric motor, delivering 2.25 kW continuously. At the
commencement of an operation, a flywheel of moment of inertia 50 kg m 2 on the machine is
rotating at 250 rpm. The pressing operation requires 4.75 kJ of energy and occupies 0.75 second.
Find the maximum number of pressing that can be made in 1 hour and the reduction in speed of the
flywheel after each pressing. Neglect friction losses.
A shaft fitted with a flywheel rotates at 250 rpm and drives a machine the resisting torque of
which varies in a cyclic manner over a period of three revolutions. The torque rises from 675 Nm to
2700 Nm in a uniform manner during 0.5 revolution and remains constant for 1 revolution, the cycle
being then repeated. If the driving torque applied to the shaft is constant and the flywheel has a
mass of 450 kg and a radius of gyration of 0.6 m, find the power necessary to drive the machine and
the percentage fluctuation of speed.
A vertical diesel engine running at 350 rpm develops 600 kW and has 4 impulses per
revolution. If the fluctuation of energy is 25 per cent of the work done during each
impulse, estimate the cross-sectional area of the rim of the flywheel required to keep the
speed within 2 rpm of the mean speed when the mean peripheral speed of the rim is 1350
m/min. Cast iron has a density of 7.2 Mg/m3
.
a. Write the balanced equation for the reaction of zinc and HCl. b. Write the equilibrium expression for the reaction of zinc and HCl. Keq = c. Should the equilibrium expression change if the size of the pieces changes? Why or not? d. Should the reaction rate change if the size of the Zn pieces changes? Why or why not? e. When the concentration of HCl is increased, what happens to the reaction rate? Is this what you expected? Why or why not?
1) A 400 V, 50 Hz 6 pole star connected three-phase induction motor consumes 75 kW with a line current of 75 A and runs at a slip of 2,5 %. If the stator iron loss is 2 kW, the windage and friction losses is 1,2 kW and the resistance between two stator terminals is 0,32 ohm, calculate:
a) the power supplied to the rotor (Ps),
b) the rotor copper loss (PcuR),
c) the power supplied to the load (Pout )
d) the efficiency and
e) the shaft torque developed.
A delta connected motor has a resistance of 850 mohm and inductance of 2,5 mH. This motor receives a line voltage of 400 V at a frequency of 50 Hz. This supply is obtained from a 50 kVA delta/star transformer. This transformer has a no load current of 2,55 A at a lagging power factor of 0,121. Fully describe the primary line current of this transformer for the given load, when it is fed by 11 kV transmission lines.
Knowing that at the instant rod BD rotates with a constant counterclockwise angular velocity @, = 2 rad/s,
determine (a) the angular velocity of rod AD and the relative velocity of collar D with respect to rod AD, (b) the
angular acceleration of rod AD and the relative acceleration of collar D with respect to rod AD.
