Force Work and Energy for Class 5 Science
Force can be defined as a push or pull. Force can change the shape, direction and speed of an object.
It can be further classified into contact and non-contact forces.
Ability to do work is termed as Energy.
Energy can neither be created nor destroyed. It can be changed from one form to another.
Types of Force and its Effects
Question 1:
What Is Atmospheric Pressure?
Answer:
The force exerted due to the weight of air around us is called atmospheric pressure.
Question 2:
What Role Does Atmospheric Pressure Play in Our Daily Life?
Answer:
Atmospheric pressure comes into play in the following situations—
- Sucking a liquid through a straw.
- Filling a dropper with a liquid.
- Sticking a rubber sucker on the wall.
Question 3:
Why Does Our Body Not Collapse Due to the Force Exerted by Atmospheric Pressure?
Answer:
Our body does not collapse due to the force exerted by atmospheric pressure as blood in our body also exerts pressure, called blood pressure. As a result, our body shape is maintained.
Question 4:
What Is the Unit of Force?
Answer:
The unit of force is Newton.
Question 5:
What Happens if the Frictional Force Between the Wheels of a Trolley and the Floor Decrease?
Answer:
If the frictional force between the wheels of a trolley and the floor decreases, the trolley cannot move smoothly on the floor.
Question 6:
Why Do Football Players Wear Spike Shoes While Playing Football?
Answer:
Football players wear spike shoes as they increase the magnitude of frictional force between the feet and the ground and help them get a better grip on the ground while running.
Question 7:
What Is Pressure?
Answer:
The force acting on the unit area of an object is called pressure.
Question 8:
Which Force Can Be Used to Gather Iron Pins From a Mixture of Plastic and Iron Pins? Give a Reason for Your Answer.
Answer:
Magnetic force can be used to gather iron pins from a mixture of plastic and iron pins. The reason is that iron pins are magnetic and are attracted by a magnet.
Question 9:
What Happens to the Sofa Springs When We Sit on a Sofa?
Answer:
The sofa springs get compressed due to the force applied while we sit on it.
Question 10:
Force Can Change the Shape of an Object. Give Examples to Prove This Fact.
Answer:
The following examples state that force can change the shape of an object—
- Change is the shape of dough when rolled with a rolling pin.
- Change in the length of spring when stretched.
- Change in the shape of a sponge when pressed.
Question 11:
Why Does a Sharp Knife Cut Objects More Effectively Than a Blunt Knife?
Answer:
Sharp knives have less area than blunt knives. While pressing a sharp knife, the force of our hand is distributed over a smaller area. Hence, more pressure is applied, helping cut an object easily.
Less pressure is produced when the force is distributed over a large area. Hence, objects are not cut properly using a blunt knife.
Question 12:
In Which of the Following Situations Will the Force Cause a Deeper Depression? Give a Reason for Your Answer.
i) A Man Standing on the Sofa. ii) a Man Lying on the Sofa.
Answer:
- In the case of a man standing on a sofa, a deeper depression would be created as the force exerted by a man's body weight would create pressure on a smaller area of the sofa.
- However, a man lying on a sofa will exert less pressure as the force applied due to the body weight would be distributed on a larger area. Hence, it will cause less depression.
Question 13:
What Will Happen if an Equal Magnitude of Force Is Applied From Both Sides of an Object?
Answer:
There would be no change in the position of an object as equal magnitudes of force will neutralise the resultant force.
Simple Machines and Levers
Question 1:
A Wheel and a Rope Make Which Simple Machine?
Answer:
A wheel and a rope together make a pulley.
Question 2:
A Ceiling Fan Comprises Several Simple Machines. Name Them.
Answer:
A ceiling fan comprises the following simple machines—
- Wheel and axle: The shaft and the base of the fan.
- Inclined plane: Blades of the fan.
- Screw: The points from where the fan is attached to the ceiling.
Question 3:
The Floor of a Bathtub Is Like an Inclined Plane. Do You Agree With This Fact? If Yes, Give the Reason for Your Answer.
Answer:
Yes, the floor of a bathtub resembles an inclined plane.
Thus, the water reaches a point from where it can be drained out of the
bathtub.
Question 4:
A Ceiling Fan Comprises Several Simple Machines. Name Them.
Answer:
Which Simple Machine Is Found in the Shoelaces of Your Shoes?
Shoelaces are like a rope and pulley system. The eyes of the shoes where the shoe laces are threaded act like a pulley. The shoe laces act like a rope.
Question 5:
The Construction of a Ladder Is Based on Which Simple Machine?
Answer:
Which Simple Machine Is Found in the Shoelaces of Your Shoes?
- The construction of a ladder is based on an inclined plane.
- The base of a ladder is an inclined plane on which the ladders are made.
Question 6:
Which Simple Machine Is Used in a Window Blind?
Answer:
Rope and pulleys are used to make a window blind.
Question 7:
Which Simple Machine Is Used to Make a Pizza Cutter?
Answer:
A wheel and axle are used to make a pizza cutter.
Question 8:
A Toilet Paper Roll on a Spinning Holder Resembles Which Simple Machine?
Answer:
A toilet paper roll on a spinning holder resembles a wheel and axle. The axle is the main axis of the holder, whereas the circular surface on which the toilet paper rolls is the wheel.
Question 9:
Which Simple Machine Is Used to Make a Door Stopper?
Answer:
A wedge is used in making a door stopper.
Question 10:
Broom Is an Example of Which Class of Lever?
Answer:
- Broom is an example of a third-class lever.
- The fulcrum is the tip where the broom's sticks are joined together.
- The point from where we hold it is the effort, and the region of the broom which is used to clean the surface is the effort.
Forms of Energy and Their Conversion
Question 1:
What Do You Understand by the Transfer of Energy?
Answer:
The movement of energy from one object to the other is called the transfer of energy.
For example, the movement of chemical energy stored in the battery to the bulb of a torch.
Question 2:
Food Gives Us the Energy to Dance. Mention the Energy Conversions Taking Place in This Situation.
Answer:
The chemical energy of food is getting converted into muscular energy.
Question 3:
What Do You Understand About Rotational Kinetic Energy?
Answer:
The energy possessed by an object in circular motion is called rotational kinetic energy. For example, a moving fan or a boy running on a circular track.
Question 4:
How Does Kinetic Energy Depend on the Mass of an Object?
Answer:
Kinetic energy is directly proportional to the mass of an object. It means that the higher the mass, the greater will be the kinetic energy and vice versa.
Question 5:
Mention the Energy Conversion That Takes Place in a Roller Coaster Ride.
Answer:
Electricity is used to operate the roller coaster. Therefore, electrical energy gets converted into mechanical energy.
Question 6:
A Man Accidentally Drops a Glass on the Floor. What Energy Conversions Take Place in This Situation?
Answer:
The glass in a person's hand possesses potential energy due to its position. As soon as it is dropped, the potential energy changes into kinetic energy. The moment the glass hits the ground, the potential energy is minimum, and kinetic energy is maximum.