LAST MINUTE REVISION SET 7
30 ASSORTED NUMERICALS
1.Two forces each of magnitude 2N act vertically upwards and downwards
respectively on two ends of a uniform rod of length 1m freely pivoted at
the centre. Determine the resultant moment of force about the midpoint
of the rod.
2. A uniform meter scale of weight 50gf is balanced at 60cm mark when a
weight of 15gf is suspended at the 10cm mark. Where must a weight
100gf be suspended to balance the meter scale.
3. Calculate the horse power of an engine which lifts 4000m 3 of water
from a depth of 50m in 49 minutes. [ g = 9.8ms -2, dH2O = 1000 kgm-3 1H.P
= 750W].
4. A body of mass 4kg moving with a velocity of 4ms -1. Find the ratio of
initial and final kinetic energy, if the mass is doubled and velocity is
tripled.
5. A spring is kept compressed by a toy cart of mass 100g. On releasing
the pressure car moves out with a speed of 0.5ms -1. Calculate the
potential energy of the compressed spring.
6. The handle of a nutcracker is 16 cm long and a nut is placed 2 cm from
its hinge. If a force of 4kgf is applied at the end of the handle to crack it,
what weight, if simply, placed on the nut will crack it?
7. An effort of 500 N is applied through 0.50 m on a machine, whose
efficiency is 90%, such that resistance is overcome through 0.04 m.
Calculate the (a) V.R. (b) M.A.(c) resistive force to be overcome.
8. A pulley system with velocity ratio 4 is used to lift a load of 100kgf
through a vertical height of 15 m. The effort required to do so is 40kgf
which is applied in the downward direction. Calculate: (a) Distance
through which effort is applied (b) Work done by the effort (c) Mechanical
advantage of pulley system (d) Efficiency of pulley system (e) Number of
pulleys in the upper and lower block. [Take g= 10 N kg-1]
9. The ratio between sine of angle of incidence and sine of angle of
refraction is 0.75 while travelling from water to air. Find refractive index of
water w.r.t air.
30 ASSORTED NUMERICALS
1.Two forces each of magnitude 2N act vertically upwards and downwards
respectively on two ends of a uniform rod of length 1m freely pivoted at
the centre. Determine the resultant moment of force about the midpoint
of the rod.
2. A uniform meter scale of weight 50gf is balanced at 60cm mark when a
weight of 15gf is suspended at the 10cm mark. Where must a weight
100gf be suspended to balance the meter scale.
3. Calculate the horse power of an engine which lifts 4000m 3 of water
from a depth of 50m in 49 minutes. [ g = 9.8ms -2, dH2O = 1000 kgm-3 1H.P
= 750W].
4. A body of mass 4kg moving with a velocity of 4ms -1. Find the ratio of
initial and final kinetic energy, if the mass is doubled and velocity is
tripled.
5. A spring is kept compressed by a toy cart of mass 100g. On releasing
the pressure car moves out with a speed of 0.5ms -1. Calculate the
potential energy of the compressed spring.
6. The handle of a nutcracker is 16 cm long and a nut is placed 2 cm from
its hinge. If a force of 4kgf is applied at the end of the handle to crack it,
what weight, if simply, placed on the nut will crack it?
7. An effort of 500 N is applied through 0.50 m on a machine, whose
efficiency is 90%, such that resistance is overcome through 0.04 m.
Calculate the (a) V.R. (b) M.A.(c) resistive force to be overcome.
8. A pulley system with velocity ratio 4 is used to lift a load of 100kgf
through a vertical height of 15 m. The effort required to do so is 40kgf
which is applied in the downward direction. Calculate: (a) Distance
through which effort is applied (b) Work done by the effort (c) Mechanical
advantage of pulley system (d) Efficiency of pulley system (e) Number of
pulleys in the upper and lower block. [Take g= 10 N kg-1]
9. The ratio between sine of angle of incidence and sine of angle of
refraction is 0.75 while travelling from water to air. Find refractive index of
water w.r.t air.
