Physics

Forces, Energy and Machines

281 Questions

Forces, energy, and machines are fundamental physics concepts focusing on mechanics, work, power, and simple machines. These topics regularly appear in general science sections of competitive exams. Use these questions to practice calculating resultant forces, mechanical advantage, and work done in various scenarios.

Resultant force calculationsMechanical advantage of leversWork and power equationsApparent weight in elevatorsBending moments

Forces, Energy and Machines Questions

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

The resultant of all the forces acting on the body in static equilibrium should be equal to 

  1. One

  2. Zero

  3. Two

  4. More than one
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The resultant of all the forces acting the body should be equal to zero. The resultant moment of all the forces acting on the body about the point of rotation should be zero.

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

The resultant moment of all the forces acting on the body about the point of rotation should be

  1. Greater than one

  2. Smaller than one

  3. Zero

  4. One
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The resultant moment of all the forces acting on the body about the point of rotation should be zero, i.e., the sum of the anticlockwise moments about the axis of rotation must be equal to the sum of the clockwise moments about the same axis.

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

A rope ladder with a length $\ell$ carrying a man ofmass $m$ at its end is attached to the basket ofballoon with a mass $\mathrm { M }$ . The entire system is in equilibrium in the air. As the man climbs up theladder into the balloon, the balloon descends bya height h. Then the potential energy of the man: 

  1. Increases by mg $( \ell - h )$

  2. Increases by mge

  3. Increases by mgh
  4. Increases by mg $( 2 \ell - h )$
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice physics units and measurement: error analysis significant figures significant figures and rounding of digits units and measurements

Find the value of following on the basis of significant figure rule:
The height of a man is $5.87532$ ft. But measurement is correct upto three significant figures. The correct height is?

  1. $5.86$ ft
  2. $5.87$ ft
  3. $5.88$ ft
  4. $5.80$ ft
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Significant figures upto three significant figures for the given question is 5.875 . Therefore, 5 is equal to 5 and we can round off the digit preceding 5 is increased by 1.


Therefore , now the correct answer vis 5.88 ft.
Therefore answer  c is correct.

Multiple choice physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

A body is acted upon by a constant force directed towards a fixed point. The magnitude of the force varies inversely as the square of the distance from the fixed point then path can be described by an equation similar to:

  1. $y=mx+c$
  2. ${ x }^{ 2 }+{ y }^{ 2 }={ r }^{ 2 }$
  3. $y=c{ x }^{ 2 }$

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

The force field is similar to gravitational field.
So, the path is parabolic or elliptical or hyperbolic.
The exact trajectory will depend on the masses and  energy of the particle.
Option(A) is equation of a straight line, it is ruled out.
Option(B) is equation for a circle and is also eqn of an ellipse with length of major axis equal to minor axis.
Option(C) is eqn of a parabola.
Hence, (D) is the best option.

Multiple choice physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

The fours basic forces in nature are.
I. Gravitational force
II. Electromagnetic force
III. Strong nuclear force
IV. Weak nuclear force
The relative magnitudes of these forces are in the order of.

  1. III $>$ II $>$ I $>$ IV
  2. III $>$ II $>$ IV $>$ I
  3. I $>$ II $>$ III $>$ IV
  4. III $>$ I $>$ II $>$ IV
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Actually the order of the four basic forces in nature in order of their relative magnitudes are strong nuclear force $>$ Electromagnetic force $>$ Weak nuclear force $>$ Gravitational force.
Multiple choice maths the integers division of integers and its properties multiplying and dividing integers multiplication of integers

Suppose we represent the distance above the ground by a positive integer and that below the ground by a negative integer, then answer the following:
An elevator descends into a mine shaft at the rate of $5$meters per minute. What will be its position after one hour? 

  1. $250$
  2. $300$
  3. $100$
  4. $50$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since, the elevator going down, so the distance covered by it will be represented by a negative integer.
Change in position of elevator in one minute = $-5 m$.
Position of the elevator after $60$ minutes = $(-5)\times 60 =-300\ m$ 

i.e. $ 300\ m$ below ground level.

Multiple choice

The work done by a force is equal to the:

  1. Force applied multiplied by the distance moved in the direction of the force

  2. Force applied multiplied by the distance moved perpendicular to the force

  3. Force applied multiplied by the time the force is applied
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Work is a scalar quantity that measures the energy transferred to or from an object by a force. It is calculated as the dot product of the force vector and the displacement vector, which is the distance moved in the direction of the force.

Multiple choice

The work done by a force on an object is equal to the product of the force and the displacement of the object in the direction of the force. The equation for work is:

  1. W = Fd

  2. W = F/t

  3. W = kx
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The work done by a force on an object is equal to the product of the force and the displacement of the object in the direction of the force. The equation for work is W = Fd, where W is the work done, F is the force, and d is the displacement of the object.

Multiple choice

What is the maximum allowable height for a ladder to be used without additional fall protection?

  1. 10 feet

  2. 15 feet

  3. 20 feet

  4. 25 feet
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In general, ladders should not be used at heights greater than 10 feet without additional fall protection, such as a safety harness or guardrails.

Multiple choice

A ladder 10 feet long leans against a wall. If the base of the ladder is 6 feet from the wall, how high up the wall does the ladder reach?

  1. 4 feet

  2. 6 feet

  3. 8 feet

  4. 10 feet
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The ladder, the wall, and the ground form a right triangle. The length of the ladder is the hypotenuse of this triangle. The distance from the base of the ladder to the wall is the adjacent side. The height of the ladder up the wall is the opposite side. Using the Pythagorean theorem, we can find the height of the ladder: √(10^2 - 6^2) = 8 feet.

Multiple choice

A ladder 12 feet long leans against a wall. If the base of the ladder is 4 feet from the wall, how high up the wall does the ladder reach?

  1. 6 feet

  2. 8 feet

  3. 10 feet

  4. 12 feet
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The ladder, the wall, and the ground form a right triangle. The length of the ladder is the hypotenuse of this triangle. The distance from the base of the ladder to the wall is the adjacent side. The height of the ladder up the wall is the opposite side. Using the Pythagorean theorem, we can find the height of the ladder: √(12^2 - 4^2) = 10 feet.

Multiple choice

A ladder 8 feet long leans against a wall. If the base of the ladder is 3 feet from the wall, how high up the wall does the ladder reach?

  1. 4 feet

  2. 5 feet

  3. 6 feet

  4. 7 feet
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ladder, the wall, and the ground form a right triangle. The length of the ladder is the hypotenuse of this triangle. The distance from the base of the ladder to the wall is the adjacent side. The height of the ladder up the wall is the opposite side. Using the Pythagorean theorem, we can find the height of the ladder: √(8^2 - 3^2) = 5 feet.

Multiple choice

The force vector of a structure is a:

  1. Column vector

  2. Row vector

  3. Square matrix

  4. Rectangular matrix
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The force vector is a column vector because it contains the forces acting on all the degrees of freedom of the structure.