Physics · Science General

Newtonian Mechanics and Forces

1,605 Questions

Newtonian mechanics studies the motion of objects and the physical laws governing them. This hub covers friction, gravitational force, inertia, and vector quantities. Mastering these fundamental physics concepts is essential for various government competitive exams.

Laws of motionFriction and inertiaVector and scalar quantitiesGravitational accelerationArchimedes principle

Newtonian Mechanics and Forces Questions

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

The centre of mass of a rigid body always lies inside the body. Is this statement true or false?

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
No it's not necessary that the centre of mass of a body should lie inside the body. Consider a circular ring, its centre of mass lies at the center of the ring where there is no content of the body. So it can also lie outside the body .
Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

A point at which a whole weight of body act vertically downward is ________.

  1. centre of gravity

  2. centre of mass

  3. centre of force

  4. centre of acceleration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The center of gravity is the point where the total gravitational force (weight) of a body is considered to act. While often coincident with the center of mass, the definition specifically refers to weight.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

In classical system:

  1. the varying mass system is not considered

  2. the varying mass system must be considered

  3. the varying mass system may be considered

  4. only varying of mass due to velocity is considered
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Classical mechanics is a broad framework that can accommodate varying mass systems, such as rockets or chains, through the application of Newton's second law in the form F = dp/dt.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

The passengers in a boat are not allowed to stand because: 

  1. This will raise the centre of gravity and the boat will be rocked

  2. This will lower centre of gravity and the boat will rocked

  3. The effective weight of system increases

  4. Of surface tension effects
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

when passengers stands up on the boat from the sitting situation , the centre of gravity moves upwards and it increases the chances of toppling of boat .

so the answer is A.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

The point through which the total weight of an object appears to act for any orientation of the object is ______.

  1. Centre of buoyancy

  2. Centre of gravity

  3. Centre of curvature

  4. Median of a triangle
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The point through which the total weight of an object appears to act for any orientation of the object is centre of gravity.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass
State whether true or false.
The position of centre of gravity of an object depends on the acceleration due to gravity at the given place.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The center of gravity is a geometric property of any object. The center of gravity is the average location of the weight of an object with mass.
Therefore the position of centre of mass has nothing to do with the acceleration due to gravity.
So, the statement is FALSE
Multiple choice physics statics and dynamics of fluid (liquid and gas) pressure in liquids and gases pressure dependence on force and area concept of pressure

Force acting per unit area is

  1. Acceleration

  2. Pressure

  3. Velocity

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pressure is defined as force per unit area. The standard unit for pressure is the Pascal, which is a Newton per square meter.

$P=\dfrac{F}{A}$

For an object sitting on a surface, the force pressing on the surface is the weight of the object, but in different orientations it might have a different area in contact with the surface and therefore exert a different pressure.

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

State the principle on which a hydraulic press works. 

  1. Archimedes principle

  2. Bernoulli's principle

  3. Pascals Law

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It works on the principle of Pascals law.
Pascal's law: Pressure on a confined fluid is transmitted undiminished and acts with equal force on equal areas and at 90 degrees to the container wall.
Uses of hydraulic press - Hydraulic presses are commonly used for forging, clinching, moulding, blanking, punching, deep drawing, and metal forming operations.

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

Hydraulic press is based upon :-

  1. Archimede's principle

  2. Bernoulli's theorem

  3. Pascal's law

  4. Reynold's number
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hydraulic press works on Pascal's principle, which states - “pressure throughout a closed system is constant.” 


In hydraulic press, there is a piston at one end of the system having a small cross-sectional area. This piston is driven by a lever. The other end of the system has small-diameter tubing. 
When a fluid is displaced, either of the pistons is pushed inward. Small piston displaces a smaller amount of volume than the large piston for a given distance of movement. The displaced fluid volume is proportional to the ratio of pistons' head areas. Hence, smaller piston moves a large distance to move large piston significantly. The large piston movement distance is equal to small piston movement distance divided by the ratio of the pistons' head areas.

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

Hydraulic machines work on the application of

  1. Pascal's law

  2. Newton's law

  3. Law of Gravity

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The hydraulic machine uses Pascal's principle, which states that states that the pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid.
The hydraulic machine is used to multiple force or to transmit force from one location to another. 
i)     hydraulic brakes
ii)    hydraulic press
ii)    hydraulic lift

Multiple choice physics machines levers and pulleys pulley pulleys

A pulley makes our work easier by changing the direction of the force.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A fixed pulley is primarily used to change the direction of the applied force, making it easier to pull a load downwards rather than lifting it upwards.

Multiple choice physics a little effort, lot of work levers and pulleys pulley pulleys

In a wheel-and-axle :

  1. wheel rotates freely on axle

  2. wheel is fixed to the axle

  3. direction of the force remains same'

  4. mechanical advantage is always more than one
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a wheel-and-axle, the wheel and the axle are rigidly connected so that they rotate together around the same axis.

Multiple choice physics machines levers and pulleys pulley pulleys

In a pulley :

  1. Load and effort are equal

  2. Load is greater than effort

  3. Load is less than effort

  4. Both have no relation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a single fixed pulley, the effort required is equal to the load (ignoring friction), as the mechanical advantage is 1.

Multiple choice physics machines levers and pulleys pulley pulleys

In a pulley:

  1. wheel is fixed over the axle

  2. effort is greater than the load

  3. mechanical advantage will be more than one

  4. wheel rotates freely over the axle
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A pulley consists of a wheel (sheave) that rotates freely on an axle, allowing the rope to move over it with minimal friction.