Maharashtra Board Textbook Solutions

Standard 6 – Science

Chapter 12 – Simple Machines

✨ 1. Classify the following as a lever, a pulley and an inclined plane :

A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife.

Ans:

  • A wedge – Inclined plane
  • A needle – Inclined plane
  • A staircase – Inclined plane
  • A slide – Inclined plane
  • The wheel of a flagpole – Pulley
  • Nutcrackers – Lever
  • Scissors – Lever
  • An opener – Lever
  • An axe – Inclined plane
  • A crane – Pulley
  • A knife – Inclined plane

✨ 2. Fill in the blanks using the proper word and complete the statements.

(a) The ……. in the centre, the ………. on one side and the …… on the other side make a lever of the first order.
Ans: The fulcrum in the centre, the load on one side and the effort on the other side make a lever of the first order.

(b) The ….. in the centre, the …….. on one side and the ……… on the other side make a lever of the second order.
Ans: The load in the centre, the fulcrum on one side and the effort on the other side make a lever of the second order.

(c) The ………. in the centre, the ……. on one side and the…….. on the other side make a lever of the third order.
Ans: The effort in the centre, the fulcrum on one side and the load on the other side make a lever of the third order.

🔧 3. Which machines will you use to do the following work? Write their types.

(a) To remove the lid of a tin.
Ans: We use a can opener.
Type of Machine: Lever

(b) To lift bricks to the top of a tall building.
Ans: We use a crane.
Type of Machine: Pulley

(c) To cut vegetables.
Ans: We use a knife or cutter.
Type of Machine: Wedge

(d) To draw water from a well.
Ans: We use a wheel and rope system.
Type of Machine: Pulley

(e) To hold a papad for roasting it.
Ans: We use a pair of tongs.
Type of Machine: Lever

✍️ 4. Write the answers to the following questions in your own words.

(a) What is meant by simple machines?
Ans: Simple machines are machines which have only one or two parts and a simple structure. They make our work easier. Examples include a knife and nutcrackers.

(b) Mention the advantages of using a machine.
Ans: The advantages of using a machine are:
(i) More work can be done in less time and with greater accuracy.
(ii) Less effort is required to complete the task.

(c) What is meant by complex machines?
Ans: A machine made up of two or more simple machines is called a complex machine. It has many parts that work together to perform a task. A bicycle is a common example of a complex machine.

(d) What is a lever? How are the orders of the lever determined?
Ans: A lever is a simple machine that has three parts: fulcrum, load, and effort.

  • Fulcrum: The fixed point on which the lever rotates.
  • Load: The weight that is to be lifted.
  • Effort: The force applied to lift the load.

The order of a lever is determined by the position of the fulcrum, load, and effort.

  • Lever of first order: The fulcrum is between the load and effort.
    Example: See-saw, crowbar
  • Lever of second order: The load is between the fulcrum and effort.
    Example: Nutcracker, wheelbarrow
  • Lever of third order: The effort is between the fulcrum and load.
    Example: Forceps, human forearm

❓ 5. Why is this so?

(a) Traveller’s bags have wheels.
Ans: Traveller’s bags have wheels so that they can be moved easily. Wheels reduce friction, which decreases the effort required to move the bag.

(b) Machines have to be maintained.
Ans: Machines have moving parts that rub against each other and create friction. Dust, rust, and wear and tear can damage the machine. Therefore, regular maintenance is necessary to keep machines working properly.

(c) A bicycle is said to be a complex machine.
Ans: A bicycle is made up of many simple machines such as a wheel and axle, levers, screws, and pulleys. All these parts work together, so a bicycle is called a complex machine.

🔍 6. Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.

Ravi and Savita sit on a sea-saw in a garden. In the meantime, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs.

Ans: In the seesaw, we have used the first-order lever. In the first-order lever, the fulcrum is between the load and effort.

In the wheelbarrow, we have used the second-order lever, which means the load is between the fulcrum and effort.

In the lemon squeezer, we have used the second-order lever, which means the load is between the fulcrum and effort.

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