Force Motion and Pressure Quiz

Which of the following instrument does not depend on pressure for it operation

• Siphon

• Force pump

• Thermometer

• Barometer

Answer explanation

A thermometer measures temperature and does not rely on pressure for its operation, unlike a siphon, force pump, and barometer, which all depend on pressure changes to function.

Bodies are weightless in space because

• the acceleration due to gravity of the earth balances that of the sun

• of the absence of air

• of the absence of the force of gravitu

• the weight of the body exactly balances the force of gravity

Answer explanation

Bodies are weightless in space primarily due to the absence of air, which means there is no air resistance acting on them. This is why astronauts experience weightlessness, not because of gravity's absence.

The statement to every action there is an equal or opposite reaction is

• the law of inertia

• Newton's second law of motion

• Newton's first law of motion

• Newton's third law of motion

Answer explanation

The statement "to every action there is an equal or opposite reaction" describes Newton's third law of motion, which states that forces always occur in pairs. This is distinct from the first and second laws, which address inertia and acceleration.

Which of the following devices does not employ the application of pressure.

• Hydraulic press

• Siphon

• Bicycle pump

• Hydrometer

Answer explanation

The siphon operates based on gravity and atmospheric pressure, not by applying pressure itself. In contrast, the hydraulic press, bicycle pump, and hydrometer all utilize pressure in their functions.

Which of the following statement is correct

• Inertia and momentum are identical

• The unit of inertia is kilogram meter per second

• Momentum is product of mass and velocity

• I and II only

Answer explanation

The correct statement is that momentum is the product of mass and velocity, defined as p = mv. Inertia is a property of mass, not a unit, and its unit is simply kilograms, not kilogram meter per second.

When a hydrometer floats in a liquid it means that the

• weight of the liquid displaced is equal to the weight of the hydrometer

• density of the hydrometer is equal than the density of the liquid

• upthrust on the hydrometer is less than the volume of the hydrometer

• volume of the portion of the hyfrometer in the liquid is equal to the volume of liquid displaces

Answer explanation

When a hydrometer floats, it indicates that the weight of the liquid displaced is equal to the weight of the hydrometer, according to Archimedes' principle. This balance allows the hydrometer to remain afloat.

An object of mass 220.0kg. Calculate its weight

• 2200.0 N

• 220.0N

• 2.20 N

• 0.22N

Answer explanation

To calculate weight, use the formula: weight = mass × gravity. Here, weight = 220.0 kg × 9.8 m/s² = 2156 N, which rounds to 2200.0 N. Thus, the correct answer is 2200.0 N.

Objects are weightless in space because

• the force of gravity exactly balances the weight of the objects

• there is no air

• there is negligible force of gravity

• the upthrust on the object is equal to the weight of the object

Answer explanation

Objects are weightless in space because there is negligible force of gravity acting on them. Unlike on Earth, where gravity is strong, in space, the gravitational pull is much weaker, leading to a sensation of weightlessness.

The centre of gravity of a body is the point

• where its original weight acts

• Where the body can be stable

• where the total mass of the body acts

• which divides the body into two equal parts

Answer explanation

The centre of gravity is the point where the total mass of the body acts, meaning it is the average location of the weight distribution. This is why the correct answer is 'where the total mass of the body acts'.

The pressure at any point in a liquid

• is not affected by acceleration due to gravity

• depends on its depth below the surface of the liquid

• is proportional to the cross sectional area of the liquid at that point

• depends on the shape of the container

Answer explanation

The pressure in a liquid increases with depth due to the weight of the liquid above. Therefore, it depends on its depth below the surface, making this the correct choice.