Questions
Which of the following statements about force is false?
- At least two objects must interact for a force to take place.
- Force has only magnitude.
- Forces applied on an object in the same direction add to one another.
- More than one force may act on an object.
- If two forces act in opposite directions on an object, the net force, acting on it, is the difference between the two forces.
Which of the following is expressed as magnitude of force?
- Direction
- Wavelength
- Strength
- Period for which the force acts
- Friction
What is the S.I. unit of force?
- Hertz
- Pascal
- Ohm
- Newton
- Ampere
Which of the following is an example of contact force?
- Like poles of magnets repelling each other
- Straw rubbed with paper attracting another straw, which is not rubbed with paper
- Pressing a lump of dough to make chapatti balls
- Water flowing down from a tap
- Electromagnets being used to pick up metallic scrap
Force acting per unit area of a surface is called
- friction
- gravity
- volume
- magnetism
- pressure
Force acting on a surface, in a direction perpendicular to it, is called
- fluid pressure
- thrust
- ampere
- magnetism
- frequency
The force by which an object is attracted towards the Earth is called its
- contact force
- friction
- weight
- thrust
- resistance
A boy was travelling for the first time in an aeroplane. As the flight took off from the airport, he got an uneasy feeling. He felt that some pressure changes had occurred. What forces were acting on the aeroplane immediately after it took off?
- Magnetism and muscular force
- Electrostatic force and magnetism
- Friction of fuel and muscular force
- Gravity and friction of air
- Magnetism and mechanical force
While scuba diving, a girl notices air bubbles underwater. She observes that the size of a bubble is small when it is deep underwater. But the size increases as it moves upwards. What could be the reason behind the increase in size of the bubble?
- It is due to gravity.
- Water enters into the bubbles to make them appear larger.
- It is due to decrease in pressure applied by water on air bubbles.
- Friction
- More air enters into the bubbles from top.
A boy was travelling with his father on a scooter. He noticed a huge truck with many big wheels. He compared the size of the wheel to that of his scooter. He then asked his father,'' why are the wheels of heavy vehicles broad and more in number.
Which of the following is the correct answer of the question asked by the boy?
- They spread out the weight.
- Heavy vehicles look stylish in that way.
- This prevents wear and tear.
- Small wheels will be required more in number.
- The vehicles look taller in that way.
Which of the following is an example for muscular force?
- Blacksmith hammering a hot piece of iron
- Magnet attracting an iron piece
- An apple falling from a tree
- A rolling ball coming to rest
- An aircraft taking off
Why do astronauts wear special space-suits?
- They look smarter in the space-suit.
- It is a protocol that those who go out into space must wear this suit.
- Space suits maintain pressure equal to the body pressure.
- As it is difficult to wash ordinary clothes in outer space.
- These suits emit light so that they can see in the darkness.
Name a device used for measuring fluid pressure.
- Manometer
- Odometer
- Seismograph
- Speedometer
- Stethoscope
Some villagers were carrying heavy pots on their heads back to their homes. Many of them complained that their heads ached badly due to the weight. A clever person among them suggested that they should remove their shirts, roll it and place it on their heads like a ring to carry the heavy pots. When this was done, the weight on their heads seemed easier to carry. What is the correct explanation for this?
- By doing this, the weight of the pots decreased.
- The weight would be equally distributed along the ring of the rolled up cloth.
- Since the position of pots was a bit elevated, the pressure was reduced.
- Wind speed decreased the pressure of the weight.
- They got some rest while rolling up their shirts.