W&E-Test-2

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Question 1:

What is the work done when a power of 1KW is sustained for a duration of 1 second?

A) 10³ J
B) 10⁵ J
C) 3.6 × 10⁵ J
D) 3.5 × 10⁶ J

Topic: Power and Work in Physics

Correct Answer: A) 10³ J

Detailed Hint:

When calculating work done, we use the formula W = Pt, where 'P' is power and 't' is time.
In this case, we have a power 'P' of 1KW, which is 1000W, and a duration 't' of 1s.
Substituting these values into the formula gives us W = (1000W)(1s), which simplifies to 10³ J.
Therefore, the correct answer is A) 10³ J.

Question 2:

How would you express the formula for work energy in a situation involving horizontal motion?

A) W = Change in K.E
B) W = Change in P.E
C) Both A and B
D) All of the above

Topic: Work Energy Theorem in Physics

Correct Answer: A) W = Change in K.E

Detailed Hint:

An object's work is equal to its change in kinetic energy (ΔK.E) plus the change in its potential energy (ΔP.E).
However, in a horizontal motion scenario, there's no height change, making the ΔP.E equals zero.
So, the work done simplifies to W = ΔK.E.
This leads us to the correct answer A) W = Change in K.E.

Question 3:

A light object A and a heavier object B possess the same linear momentum. How does the kinetic energy of A compare to that of B?

A) Greater than that of B
B) Equal to that of B
C) Smaller than that of B
D) Infinite

Topic: Kinetic Energy and Momentum in Physics

Correct Answer: A) Greater than that of B

Detailed Hint:

Kinetic energy and momentum are closely related; however, they respond differently to mass and velocity.
For two objects with the same momentum, the object with less mass (in this case, the lighter object A) must have a higher velocity.
The square root of kinetic energy equals the velocity, A's kinetic energy is greater than B's, given the higher velocity.
Therefore, the correct answer is A) Greater than that of B.

Question 4:

What happens to the momentum of a particle if its kinetic energy is increased fourfold?

A) Remains the same
B) Doubles
C) Quadruples
D) Halves

Topic: Relationship between Kinetic Energy and Momentum

Correct Answer: B) Doubles

Detailed Hint:

K.E = p²/2m, where m is the particle's mass, is the equation that describes the relationship between kinetic energy (K.E) and momentum (p).
If the kinetic energy is quadrupled (made four times larger), the momentum is doubled, considering the square root relationship between K.E and p.
Hence, the correct answer is B) Doubles.

Question 5:

Which of the following factors does the calculation of work not rely on?

A) Force
B) Displacement
C) Time
D) All of the above

Topic: Principles of Work in Physics

Correct Answer: C) Time

Short Hint:

The formula to calculate work is W = Fd cosθ, where `F` represents force, `d` denotes displacement, and `θ` is the angle between the force and displacement.
As you can see, there's no mention of time in this formula, indicating that work is independent of time.
Hence, the correct answer is C) Time.

Question 6:

Two bodies, with masses m1 and m2, have identical kinetic energy and are both moving in the same direction. The same constant force “F” is applied in the opposite direction to both masses. If m1 is four times m2, what is the ratio of m1's stopping distance to m2's?

A) 1 : 4
B) 1 : 2
C) 4 : 1
D) 1 : 1

Topic: Force, Mass, and Motion in Physics

Correct Answer: D) 1 : 1

Short Hint:

Given two bodies with the same kinetic energy and opposite forces applied, they'll stop at the same distance despite the difference in their masses.
This is because the stopping distance depends on the kinetic energy and the force applied, not the mass of the bodies.
Therefore, the correct answer is D) 1 : 1.

Question 7:

Which of the following values represents the greatest amount of work done?

A) +100 J
B) -500 J
C) +200 J
D) -1000 J

Topic: Quantifying Work in Physics

Correct Answer: D) -1000 J

Detailed Hint:

When comparing work values, the magnitude of work is considered, not the sign.
The sign (negative or positive) merely represents the angle between the force and displacement.
Thus, the greatest work done is represented by the highest magnitude, disregarding the sign.
Therefore, the correct answer is D) -1000 J.

Question 8:

A worker hauls a 15kg load of cement up to a rooftop that is 10m high. What is the total work done? Assume gravity to be 10m/s².

A) 150 J
B) 100 J
C) 1500 J
D) 750 J

Topic: Work and Energy Principles in Physics

Correct Answer: C) 1500 J

Detailed Hint:

The potential energy (P.E) of an object at a height can be calculated by the formula P.E = mgh, where `m` is the mass of the object, `g` is the gravitational acceleration, and `h` is the height.
Substitute the given values into the formula, P.E = (15kg)(10m/s²)(10m) = 1500 Joules.
Therefore, the correct answer is C) 1500 J.

Question 10:

There is a small object of mass 1g that moves in a circular path with a radius of 0.5m. It moves at a constant speed of 2m/s. What is the total work done on the object after one complete revolution?

A) 0 J
B) 2 J
C) 1 J
D) 4 J

Topic: Work and Circular Motion in Physics

Correct Answer: A) 0 J

Detailed Hint:

In circular motion, the displacement after a complete revolution becomes zero since the object comes back to its initial position.
As a result, the formula W = Fd cosθ becomes 0J, since displacement is equal to zero (0).
Therefore, the correct answer is A) 0 J. This means that no work is done on an object in circular motion when it completes one full revolution.

Question 11:

A light bulb uses 60 watts of power. Calculate the total energy consumed by the light bulb within a span of 2 seconds.

A) 10 J
B) 30 J
C) 60 J
D) 120 J

Topic: Energy Consumption in Electricity

Correct Answer: D) 120 J

Short Hint:

The energy consumed by a device can be calculated by the formula `E = Pt`, where `E` represents energy, `P` represents power, and `t` represents time.
Substituting the provided values in the formula gives `E = 60 watts * 2 seconds = 120 Joules`.
Therefore, the correct answer is D) 120 J.

Question 12:

At which angle between the force `F` and displacement `d` is the work done reduced to half of its maximum value?

A) 60°
B) 30°
C) 45°
D) 90°

Topic: Relationship of Work with Force and Displacement

Correct Answer: A) 60°

Short Hint:

The work done can be calculated by the formula `W = Fd cosθ`, where `θ` is the angle between the force and displacement.
As per the cosine function, `cos 60° = 1/2`. Thus, at 60°, the work done is half of its maximum value.
Therefore, the correct answer is A) 60°.

Question 15:

A toy chest is moved across a flat surface for a distance of 2m using a force of 10N, which is angled 30° from the vertical. How much work is accomplished?

A) 6 J
B) 10 J
C) 12 J
D) 8 J

Topic: Work Done Against an Angle

Correct Answer: B) 10 J

Detailed Hint:

The formula for work done is W = Fd cosθ, where F represents the force, d is the displacement, and θ is the angle between the direction of force and displacement.
We subtract 30 degrees from 90 degrees to find the angle for the cosine function since the force's direction is given relative to the vertical. The angle becomes 60 degrees.
Substituting the given values gives W = (10)(2)(cos 60°) = B) 10 J.

Question 16:

A 2kg object possesses a momentum of 2Ns. What is the kinetic energy of the object?

A) 1 J
B) c² J
C) 3 J
D) 4 J

Topic: Relationships between Momentum and Kinetic Energy

Correct Answer: A) 1 J

Detailed Hint:

The formula to calculate kinetic energy using momentum and mass is K.E = p²/2m, where p is the momentum and m is the mass of the object.
Substituting the given values in the formula gives K.E = (2Ns)² / (2*2kg) = 1 Joule.
Therefore, the correct answer is A) 1 J.

Question 17:

A lifting device is tasked with raising a 100 kg object vertically, achieving a speed of 5 m/s. What would the engine's power output be in this scenario?

A) 2 kW
B) 10 kW
C) 5 kW
D) 4 kW

Topic: Power in Mechanical Systems

Correct Answer: C) 5 kW

Detailed Hint:

In order to calculate power, we need to multiply force by velocity. The force can be given as the product of mass and gravity, i.e., mg.
Given m = 100 kg, g = 10 m/s², and v = 5 m/s, substituting these values into the formula gives P = 100 kg * 10 m/s² * 5 m/s = 5000 W or 5 kW.
Therefore, the correct answer is C) 5 kW.

Question 18:

What does the gravitational potential energy per unit mass at a given point represent?

A) Gravitational field
B) Gravitational potential
C) Gravitational potential energy
D) None of these

Topic: Gravitational Potential Energy

Correct Answer: B) Gravitational potential

Detailed Hint:

As a result of gravitational potential, mass per unit has gravitational potential energy.
Therefore, the correct answer is B) Gravitational potential.

Question 19:

An object's force-displacement (F-d) graph is represented by a straight line that has a positive slope. If the graph's height and width are 4 units and 2 units respectively, what is the amount of work done on the object?

A) Zero
B) 4 units
C) 8 units
D) 2 units

Topic: Work Calculations from Force Displacement Graphs

Correct Answer: B) 4 units

Short Hint:

The work done on an object can be calculated from a Force-displacement graph as the area under the graph.
In this case, the area of the graph is given by the formula for the area of a triangle, ½ base * height, which results in ½(2)(4) = 4 units.
Therefore, the correct answer is B) 4 units.

Question 20:

What is the equivalent of the effort needed to bring a mobile object to a standstill?

A) The object's speed
B) The object's kinetic energy
C) The multiplication of the object's mass and acceleration
D) The product of the object's mass and velocity

Topic: Work and Energy

Correct Answer: B) The object's kinetic energy

Short Hint:

The work needed to stop a moving object is equal to its changed kinetic energy, which is essentially the kinetic energy the object originally had.
Therefore, the correct answer is B) The object's kinetic energy.

Question 21:

A force of 20N pushes a 5kg block, causing it to move 4m from rest in the x-direction and gain a kinetic energy of 40J. What angle does the applied force make with the x-axis?

A) 0°
B) 30°
C) 45°
D) 60°

Topic: Force, Angle, and Kinetic Energy

Correct Answer: D) 60°

Short Hint:

The work-energy theorem states that the work done on an object is equivalent to the change in its kinetic energy.
By equating the work done (which is force times displacement times cosine of the angle between them) to the acquired kinetic energy, we can solve for the angle, resulting in 60°.
Therefore, the correct answer is D) 60°.

Question 22:

The work done by a force on an object depends on:

A) The initial speed of the object
B) The distance traversed by the object
C) The object's mass
D) The angle between the displacement vector and the force vector

Topic: Factors Affecting Work Done

Correct Answer: D) The angle between the displacement vector and the force vector

Short Hint:

The work done by a force on an object depends on the component of the force in the direction of displacement multiplied by the magnitude of displacement. This can be expressed as W = Fcosθd, where θ is the angle between the force and displacement vectors.

Question 23:

Calculate the work done by a force given its coordinates (Fx, Fy, Fz) = (2, 4, 6) and displacement coordinates (dx, dy, dz) = (0, 10, 0).

A) 20 J
B) 26 J
C) 40 J
D) Zero

Topic: Work Calculation from Force and Displacement

Correct Answer: C) 40J

Detailed Hint:

The work formula in terms of force and displacement in three dimensions is W = Fx*dx + Fy*dy + Fz*dz.
Substituting the given coordinates into the formula results in W = (2)(0) + (4)(10) + (6)(0), giving 40J.
Hence, the correct answer is C) 40J.

Question 24:

Out of the following options, which object has the highest kinetic energy?

A) Object with mass 3M and velocity V
B) Object with mass 2M and velocity 3V
C) Object with mass 3M and velocity 2V
D) Object with mass M and speed 4V

Topic: Comparison of Kinetic Energy

Correct Answer: B) Object with mass 2M and velocity 3V

Detailed Hint:

The kinetic energy (K.E) formula is ½mv². The kinetic energy is maximum when the product of mass (M) and velocity squared (v²) is maximum.
In option B, this product is maximum.
Therefore, the correct answer is B) Object with mass 2M and velocity 3V.

Question 25:

Objects A and B exist such that the mass of object A is half of object B, and both objects have the same momentum. What is the kinetic energy of object A in relation to object B?

A) K⋅EA = K⋅EB
B) K⋅EA = ½K.EB
C) K⋅EA = 2K⋅EB
D) K⋅EA = 4K⋅EB

Topic: Kinetic Energy in Relation to Momentum and Mass

Correct Answer: C) K⋅EA = 2K⋅EB

Detailed Hint:

If objects of different masses have the same momentum, the object with the lighter mass will have greater kinetic energy.
In this case, since object A has half the mass of object B but the same momentum, the kinetic energy of object A will be twice that of object B.
Therefore, the correct answer is C) K⋅EA = 2K⋅EB.

Question 26:

What is the equivalent SI unit for power, also known as a watt?

A) Kgm²s⁻³
B) Kgms⁻²
C) Kgm²s⁻²
D) None of the above

Topic: Units of Power

Correct Answer: A) Kgm²s⁻³

Detailed Hint:

Power is a measure of the rate at which work is done or energy is transferred.
Watts (W) are SI units of power, equal to one joule per second and expressed as Kgm²s⁻³.
Therefore, the correct answer is A) Kgm²s⁻³.

Question 27:

The energy expended in overcoming friction is invariably transformed into what kind of energy?

A) Kinetic energy
B) Potential energy
C) Mechanical energy
D) Heat or thermal energy

Topic: Work Against Friction and Energy Conversion

Correct Answer: D) Heat or thermal energy

Short Hint:

When work is done against friction, the energy is not lost but instead transformed.
This expended energy is invariably converted into heat or thermal energy.
Hence, the correct answer is D) Heat or thermal energy.

Question 28:

An object weighing 10g is whirled 100 revolutions per second in a vertical circle of 2m diameter, attached to a string. What is the total work done on the stone?

A) Zero
B) 19.8 J
C) 4.9 J
D) 9.8 J

Topic: Work Done on a Body in Circular Motion

Correct Answer: A) Zero

Short Hint:

When a body is moving in a circular path, the centripetal force acting on it is perpendicular to the motion of the body.
Force and displacement are defined as the dot product of work. When these two are perpendicular, the work done is zero.
Therefore, the correct answer is A) Zero.

Question 29:

How would you define work in physics?

A) As the product of force and displacement
B) As the dot product of force and displacement
C) Combined displacement magnitude and applied force component corresponding to displacement direction
D) Both B and C

Topic: Definition of Work in Physics

Correct Answer: D) Both B and C

Short Hint:

Work is defined as the dot product of the applied force and the displacement caused by the force.
It can also be described as the product of the magnitude of displacement and the component of the force in the direction of displacement.
Therefore, the correct answer is D, Both B and C.

Question 30:

What denotes a conservative field?

A) The work done within the field is independent of the path taken
B) The work done on a closed path within the field is always zero
C) Both A and B
D) The work is constantly negative

Topic: Properties of a Conservative Field

Correct Answer: C) Both A and B

Short Hint:

A conservative field is defined by the fact that the work done within it does not depend on the path followed.
Additionally, in a conservative field, the total work done on a body moving along a closed path is zero.
These two properties combined define a conservative field.
Therefore, the correct answer is C, Both A and B.

Question 1:

Topic: Power and Work in Physics

Question 2:

Topic: Work Energy Theorem in Physics

Question 3:

Topic: Kinetic Energy and Momentum in Physics

Question 4:

Topic: Relationship between Kinetic Energy and Momentum

Question 5:

Topic: Principles of Work in Physics

Question 6:

Topic: Force, Mass, and Motion in Physics

Question 7:

Topic: Quantifying Work in Physics

Question 8:

Topic: Work and Energy Principles in Physics

Question 10:

Topic: Work and Circular Motion in Physics

Question 11:

Topic: Energy Consumption in Electricity

Question 12:

Topic: Relationship of Work with Force and Displacement

Question 15:

Topic: Work Done Against an Angle

Question 16:

Topic: Relationships between Momentum and Kinetic Energy

Question 17:

Topic: Power in Mechanical Systems

Question 18:

Topic: Gravitational Potential Energy

Question 19:

Topic: Work Calculations from Force Displacement Graphs

Question 20:

Topic: Work and Energy

Question 21:

Topic: Force, Angle, and Kinetic Energy

Question 22:

Topic: Factors Affecting Work Done

Question 23:

Topic: Work Calculation from Force and Displacement

Question 24:

Topic: Comparison of Kinetic Energy

Question 25:

Topic: Kinetic Energy in Relation to Momentum and Mass

Question 26:

Topic: Units of Power

Question 27:

Topic: Work Against Friction and Energy Conversion

Question 28:

Topic: Work Done on a Body in Circular Motion

Question 29:

Topic: Definition of Work in Physics

Question 30:

Topic: Properties of a Conservative Field

Test Results