Exploring Forces Class 8 MCQ
hardExploring Forces Class 8 MCQ
Exploring Forces Class 8 MCQ
Question 1.
What is the SI unit of force?
(a) Joule
(b) Newton
(c) Pascal
(d) Watt
Answer:
(b) Newton
Question 2.
Which of the following is a noncontact force?
(a) Frictional force
(b) Muscular force
(c) Gravitational force
(d) Tension force
Answer:
(c) Gravitational force
Question 3.
What happens to an object at rest when balanced forces act on it?
(a) It moves in the direction of the greater force.
(b) It remains at rest.
(c) It accelerates.
(d) It changes shape.
Answer:
(b) It remains at rest.
Question 4.
When a ball is thrown upwards, which force acts against its motion?
(a) Magnetic force
(b) Electrostatic force
(c) Gravitational force
(d) Muscular force
Answer:
(c) Gravitational force
Question 5.
What is the effect of friction on a moving object?
(a) It increases the speed of the object.
(b) It has no effect on the object.
(c) It decreases the speed of the object.
(d) It changes the direction of the object.
Answer:
(c) It decreases the speed of the object.
Question 6.
If two balloons rubbed with a woollen cloth are brought near each other, what will happen?
(a) They will attract each other.
(b) They will repel each other.
(c) They will remain unaffected.
(d) They will burst.
Answer:
(b) They will repel each other.
Question 7.
What is the buoyant force?
(a) The force exerted by a solid object.
(b) The force exerted by a liquid in an upward direction on an object.
(c) The force that causes friction.
(d) The force that pulls objects towards the Earth.
Answer:
(b) The force exerted by a liquid in an upward direction on an object.
Question 8.
Which of the following statements is true regarding mass and weight?
(a) Mass changes with location, but weight does not.
(b) Weight changes with location, but mass does not.
(c) Both mass and weight change with location.
(d) Neither mass nor weight change with location.
Answer:
(b) Weight changes with location, but mass does not.
Question 9.
What type of force is applied when a child lifts a school bag?
(a) Gravitational force
(b) Muscular force
(c) Frictional force
(d) Magnetic force
Answer:
(b) Muscular force
Question 10.
Why do we sometimes slip on smooth surfaces like ice?
(a) There is too much friction.
(b) There is no friction.
(c) The surface is too rough.
(d) The object is too heavy.
Answer:
(b) There is no friction.
Case Stydy
I. The Effect of Buoyancy on Objects in Water
When three objects of the same size and shape but made from different materials are placed in water, they exhibit varying depths of submersion. This phenomenon is primarily due to the principle of buoyancy, which states that an object will float or sink based on its density relative to the fluid. For instance, if object 1 is made of a denser material than object 2 and 3, it will sink deeper. Understanding buoyancy helps us comprehend why some objects float while others do not, illustrating the interaction between gravitational and buoyant forces.
Question 1.
Which of the following statements best describes why an object sinks or floats in water?
(a) An object will sink if it is heavier than the water.
(b) An object will float if its density is less than that of the water.
(c) An object will float if it is made of a solid material.
(d) An object will sink if it is made of a liquid.
Answer:
(b) An object will float if its density is less than that of the water.
Question 2.
According to Archimedes' Principle, what happens to an object that is fully or partially immersed in a fluid?
(a) It experiences a downward force equal to its weight.
(b) It experiences an upward force equal to the weight of the fluid displaced.
(c) It experiences no force at all.
(d) It experiences a force that is always greater than its weight.
Answer:
(b) It experiences an upward force equal to the weight of the fluid displaced.
Question 3.
An object will float in a fluid if the force acting on it is equal to the gravitational force pulling it down.
Answer:
buoyant
Question 4.
The phenomenon where a less dense object floats on a denser fluid is known as .............
Answer:
buoyancy
Question 5.
An object made of a denser material than water will always float on the surface of the water. (True/False)
Answer:
False
II. The Interaction of Charged Objects
Static electricity provides an excellent example of forces at work through interactions between charged objects. When a balloon is rubbed against wool, it acquires a charge and can attract small pieces of paper. This occurs because the balloon and wool acquire opposite charges, demonstrating the principle that unlike charges attract. This electrostatic force is a noncontact force, illustrating how forces can act at a distance. Exploring these interactions deepens our understanding of fundamental electrical principles and their practical applications in technology.
Question 1.
When a balloon is rubbed with wool, it acquires a charge. What type of charge does the balloon acquire?
(a) Positive charge
(b) Negative charge
(c) No charge
(d) Neutral charge
Answer:
(b) Negative charge
Question 2.
What is the force called that is exerted by a charged body on another charged body or an uncharged body?
(a) Gravitational force
(b) Magnetic force
(c) Electrostatic force
(d) Frictional force
Answer:
(c) Electrostatic force
Question 3.
When two objects with the same type of charge are brought close together, they will ............each other.
Answer:
repel
Question 4.
The force that pulls objects towards the Earth is known as ............force.
Answer:
gravitational
Question 5.
Electrostatic forces can only act when two charged objects are in direct contact with each other. (True/False)
Answer:
False