Download App

Science M.C.Q. [1 M]

Work and Energy · Gujarat Board (GSEB) STD 9 (GSEB - English Medium). 22 questions.

Questions

M.C.Q. [1 M]

🎯

Test yourself on this topic

22 questions · timed · auto-graded

Question 11 Mark
The device which converts mechanical energy into energy which runs our microwave oven is:
  1. Electric motor.
  2. Alternator.
  3. Turbine.
  4. Electric heater.
Answer
  1. Alternator.

Explanation:

Alternator is the device that converts mechanical energy into energy, which runs in microwave oven.

View full question & answer→
Question 21 Mark
Which one of the following statements about power stations is not true?
  1. Hydroelectric power stations use water to drive turbines.
  2. In a power station, turbines drive generators.
  3. Electricity from thermal power stations differs from that produced in hydroelectric power stations.
  4. In hydroelectric power stations and thermal power stations, alternators produce electricity.
Answer
  1. Electricity from thermal power stations differs from that produced in hydroelectric power stations.

Explanation:

Electricity produced in a hydroelectric power station is similar to electricity produced in thermal power plants.

View full question & answer→
Question 31 Mark
When an object falls freely towards the earth, then its total energy:
  1. Increases.
  2. Decreases.
  3. Remains constant.
  4. First increases and then decreases.
Answer
  1. Remains constant.

Explanation:

Total energy of a freely falling object remains conserved.

View full question & answer→
Question 41 Mark

The work done on an object does not depend on the:

  1. Displacement.
  2. Angle between force and displacement.
  3. Force applied.
  4. Initial velocity of the object.
Answer
  1. Initial velocity of the object.

Explanation:

The work done on an object does not depend upon the initial velocity of the moving object.

View full question & answer→
Question 51 Mark

 In case of negative work, the angle between the force and displacement is:

  1. 0°
  2. 45°
  3. 90°
  4. 180°
Answer
  1. 180°

Explanation:

Work done is negative when the direction of force is opposite to the direction of motion. So, the angle between force and displacement in the case of negative work.

View full question & answer→
Question 61 Mark

A girl weighing 400N climbs a vertical ladder. If the value of g be 10ms2, the work done by her after climbing 2m will be:

  1. 200J
  2. 800J
  3. 8000J
  4. 2000J
Answer
  1. 800J

Explanation:

Weight of the girl (W) = 400N

Vertical height (h) = 2m

Acceleration due to gravity (g) = 10m/s2

We can calculate the work done against gravity in moving a body of mass (m) by a height (h)  as,

Work done in lifting a body = (Weight of body)(Vertical distance)

So,

W = (m)(g)(h)

So,

Work done in lifting a body

= (400)(2)J

= 800J

View full question & answer→
Question 71 Mark

An iron sphere of mass 10kg has the same diameter as an aluminium sphere of mass 3.5kg. Both the spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same:

  1. Acceleration.
  2. Momentum.
  3. Potential energy.
  4. Kinetic energy.
Answer
  1. Acceleration.

Explanation:

Momentum, potential energy and kinetic energy depend on the mass of the body. So, the answer is acceleration as it is independent of mass.

View full question & answer→
Question 81 Mark

A car is accelerated on a levelled road and attains a speed of 4 times its initial speed. In this process, the kinetic energy of the car:

  1. Does not change.
  2. Becomes 4 times that of initial kinetic energy.
  3. Becomes 8 times that of initial kinetic energy.
  4. Becomes 16 times that of initial kinetic energy.
Answer
  1. Becomes 16 times that of initial kinetic energy.

Explanation:

Kinetic energy of a body is directly proportional to the square of the velocity. So, the kinetic energy will become 16 times its initial value if the velocity is increased 4 times.

View full question & answer→
Question 91 Mark

A car is accelerated on a levelled road and acquires a velocity 4 times of its initial velocity. During this process, the potential energy of the car:

  1. Does not change.
  2. Becomes twice that of initial potential energy.
  3. Becomes 4 times that of initial potential energy.
  4. Becomes 16 times that of initial potential energy.
Answer
  1. Does not change.

Explanation:

Potential energy of an object depends only on its position above the ground and mass. So, the potential energy of a car traveling on a leveled road does not change.

View full question & answer→
Question 101 Mark

The momentum of a bullet of mass 20g fired from a gun is 10kg m/s. The kinetic energy of this bullet in kJ will be:

  1. 5
  2. 1.5
  3. 2.5
  4. 25
Answer
  1. 2.5

Explanation:

Mass of the bullet, (m), = 0.02 gm

Momentum of the bullet, (P) = 10kg.m/s

The relation between momentum, mass and kinetic energy is as follows:

$\text{K.E.}=\frac{1}{2}\Big(\frac{\text{p}^2}{\text{m}}\Big)$

So,

$\text{K.E.}=\frac{1}{2}\Big(\frac{(10)^2}{0.02}\Big)\text{J}$

$=\frac{100}{0.04}\text{J}$

$=2500\text{J}$

$2.5\text{KJ}$

View full question & answer→
Question 111 Mark

Each of the following statement describes a force acting. Which force is causing work to be done?

  1. The weight of a book at rest on a table.
  2. The pull of a moving railway engine on its coaches.
  3. The tension in an elastic band wrapped around a parcel.
  4. The push of a person's feet when standing on the floor.
Answer
  1. The pull of a moving railway engine on its coaches.

Explanation:

  1. The weight of a book at rest on a table cannot do any work as the book is at rest. So, the work done by this force is zero.
  2. The pulling force applied by the railway engine on its coaches is doing work, as the force applied by the engine results in the motion of the coaches.
  3. The tension force in an elastic band wrapped around a parcel cannot do any work, as there is no motion of the parcel because of the tension force of the rubber band.
  4. The push of a person’s feet on a floor when he is standing cannot do any work because there is no motion involved due to the applied force.
View full question & answer→
Question 121 Mark

A girl is carrying a school bag of 3kg mass on her back and moves 200m on a levelled road. If the value of g be 10m/s2, the work done by the girl against the gravitational force will be:

  1. 6000J
  2. 0.6J
  3. 0J
  4. 6J
Answer
  1. 0J

Explanation:

The girl is moving with the bag on a levelled road. Her direction of motion is perpendicular to the direction of gravitational force. So, work done by the girl against gravity is zero.

View full question & answer→
Question 131 Mark

Which of the following does not possess the ability to do work not because motion?

  1. A sparrow flying in the sky.
  2. A sparrow moving slowly on the ground.
  3. A sparrow in the nest on a tree.
  4. A squiral going up a tree.
Answer
  1. A sparrow in the nest on a tree.

Explanation:

We will justify all statements one by one as:

  1. A sparrow flying in the sky possesses kinetic energy, which can be transformed into work.
  2. A sparrow moving slowly on the ground possesses kinetic energy, which can be transformed into work.
  3. A sparrow in the nest does not possess any kinetic energy as it is at rest. It does not possess the ability to do work in terms of motion of the body.
  4. A squirrel going up a tree possesses kinetic energy, which can be transformed into work.
View full question & answer→
Question 141 Mark

Water stored in a dam possesses:

  1. No energy.
  2. Electrical energy.
  3. Kinetic energy.
  4. Potential energy.
Answer
  1. Potential energy.

Explanation:

Water stored in a tank possesses gravitational potential energy because of its position above the ground.

View full question & answer→
Question 151 Mark
How much energy does a 100W electric bulb transfer in 1 minute?
  1. 100J
  2. 600J
  3. 3600J
  4. 6000J
Answer
  1. 6000J

Explanation:

Power, (P) = 100W

Time duration, (t) = 60s

Now, we can calculate the electrical energy consumed as,

Energy consumed = (Power)(Time)

So,

Energy consumed

 = (100)(60)J

= 6000J

So, the energy consumed is 6000 J.

View full question & answer→
Question 161 Mark
An electric motor raises a load of 0.2kg, at a constant speed, through a vertical distance of 3.0m in 2s. If the acceleration power stations and thermal power stations, alternators produce electricity.
  1. 0.3
  2. 1.2
  3. 3.0
  4. 6.0
Answer
  1. 3.0

Explanation:

Mass of the load (m1) = 0.2kg

Height (h) = 3m

Acceleration due to gravity (g) = 10m/s2

Time taken  (t) = 2s

We can calculate the work done against gravity as,

Work done by the car = (Weight of body)(Vertical distance)

= (0.2)(10)(3)J

= 6J

Now, we can calculate the power of the boy as,

$\text{Power}=\frac{\text{Work done}}{\text{Time}}$

So,

$\text{Power}=\frac{6}{2}\text{W}$

$=3\text{W}$

So, the power is 3W.

View full question & answer→
Question 171 Mark
Which one of the following is not the unit of energy?
  1. Joule.
  2. Newton-metre.
  3. Kilowatt.
  4. Kilowatt-hour.
Answer
  1. Newton-metre.

Explanation:

Kilowatt is the unit of power.

View full question & answer→
Question 181 Mark
A stone is thrown upwards as shown in the diagram. When it reaches P, which of the following has the greatest value for the stone?

  1. Its Acceleration.
  2. Its kinetic energy.
  3. Its potential energy.
  4. Its weight.
Answer
  1. Its potential energy.

Explanation:

When a stone is thrown vertically upwards, the following conclusions can be done for point P:

  1. The acceleration for the entire journey of the stone is constant, as acceleration due to gravity near the surface of the earth is constant.
  2. The velocity of the stone at P will be the least. Hence, kinetic energy at this point will be the least.
  3. The stone is at a maximum height at point P. Hence, the potential energy is the maximum at P.
  4. Weight of the stone will remain nearly constant, as acceleration due to gravity near the surface of the earth is constant.
View full question & answer→
Question 191 Mark
The commercial unit of energy is:
  1. Watt.
  2. Watt-hour.
  3. Kilowatt-hour.
  4. Kilowatt.
Answer
  1. Kilowatt-hour.

Explanation:

Kilowatt-hour is the commercial unit of electricity.

View full question & answer→
Question 201 Mark
A microphone converts:
  1. Electrical energy into sound energy in ordinary telephone.
  2. Microwave energy into sound energy in a mobile phone.
  3. Sound energy into mechanical energy in a stereo system.
  4. Sound energy into electrical energy in public address system.
Answer
  1. Sound energy into electrical energy in public address system.

Explanation:

A microphone converts sound energy into electrical energy in public address systems.

View full question & answer→
Question 211 Mark
Which of the following energy change involves frictional force?
  1. Chemical energy to heat energy.
  2. Kinetic energy to heat energy.
  3. Potential energy to sound energy.
  4. Chemical energy to kinetic energy.
Answer
  1. Kinetic energy to heat energy.

Explanation:

Frictional force is responsible for heating up of the tires of a moving vehicle. In such a situation, kinetic energy is converted into heat energy due to the frictional force.

View full question & answer→
Question 221 Mark
An object is falling freely from a height x. After it has fallen a height, it will possess:
  1. Only potential energy.
  2. Only kinetic energy.
  3. Half potential and half kinetic energy.
  4. Less potential and more kinetic energy.
Answer
  1. Half potential and half kinetic energy.

Explanation:

During the free fall, potential energy is gradually converted into kinetic energy. At half of the maximum height, energy is equally distributed in the form of potential and kinetic energy.

View full question & answer→
Generate Paper FreeAll Work and Energy topics
M.C.Q. [1 M] - Science STD 9 Questions - Vidyadip