S C I E N C E - IX
Mass of the block = 2 kg
8 × 5 × 1
= 2 × 10 = 20 N
Area of contact = 5 × 1 cm
= 0.0005 m
= 40000 Pascal.
Area of contact = 8 ×5 = 40 cm
= 0.0040 m
= 5000 Pascal.
Pressure = thrust / area
1 pascal is the pressure acting on a surface of area
1 square metre by a thrust of 1 newton.
Thrust = Weight of body = 500 N
Pressure = thrust/ area = 500/2.5 = 200 Pascal
[CBSE Marking Scheme, 2016]
Archimedes’ principle states that an object will
experience an upward force and displaces the liquid
in which it is immersed partially or completely;
if the weight of liquid displaced is more than the
weight of body, then the body will float.
In submarines and ships, the body is designed in
such a way that it displaces more water than its
weight and hence it floats.
: to determine the purity of sample of
- to determiner the of liquids.
1 + 2 + 2 = 5
By making the area half, pressure will be doubled.
This is because pressure is the thrust per unit area,
Thus, pressure is directly proportional to force and
inversely proportional to area.
A body will float in a liquid if the liquid displaced by
the immersed part of the body in liquid is equal to
the weight of the body. In case of iron ship, which is
hollow from within, the weight of water displaced
by the ship is more than the weight of the ship and
hence, it does not sink in water. But in case of iron
needle which is compact
, not hollow and the
density of iron is more than that of the weight of
water displaced by iron needle is much less than its
own weight. Hence, it sinks in water.
No, the buoyant force is not same in all fluids
for a given body. The buoyant force on the body
immersed in a fluid is directly proportional to
the density of the fluid in which the body is
Buoyant force on the body = Volume of the
body immersed in fluid × Density of the fluid
× Acceleration due to gravity (
= 1·8 × 1020 × 10
= 18,360 N.
1 + 2 = 3
From the question,
Weight of solid X in air (W
) = 180 g
Weight of solid X in water (W
) = 150 g
Relative density of solid (X) = ?
R.D. of solid
Weight of solid in air
Loss of weight of solid in water
Therefore, the relative density (R.D.) of X is 6.