1. Answer: (b) atmospheric pressure
Explanation: That pressure is called atmospheric pressure, or air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to Earth. Atmospheric pressure is commonly measured with a barometer.
2. Answer: (d) pressure
Explanation: Pressure is defined as force per unit area. The standard unit for pressure is the Pascal, which is a Newton per square meter. P = F/A
3. Answer: (a) Push or pull
Explanation: Force is a push or a pull in a particular direction that changes the orientation of the object.
4. Answer: (b) gravitational force
Explanation: The attraction force exerted by the earth on any object is called or is termed gravity.
5. Answer: (b) Contact
Explanation: Muscular force is a contact force. The electrostatic force is a non-contact force. Contact Force is a force that can be applied only when it is in contact with an object is called a contact force.
6. Answer: (b) electrostatic force
Explanation: The force exerted by an electrostatic charge or an electrically charged object is known as electrostatic force. An electrically charged object can exert an electrostatic force on another body, be it a charged body or an uncharged body.
7. Answer: (b) muscular force
Explanation: The force caused by the action of muscles in our body is known as muscular force.
8. Answer: (b) weight
Explanation: Spring balance is used to determine the force acting on the object (weight). Spring balance works on the principle of Hooke's law.
9. Answer: (b) difference between two forces
Explanation: Forces applied on an object in the same direction add to one another.If two forces act in the opposite directions on an object, the net force acting on it is the difference between the two forces.
10. Answer: (c) magnitude
Explanation: The strength of a force is expressed by its magnitude. The magnitude of a force is expressed in the SI unit of force called Newton.
11. Answer: (c) Both by the state of rest or motion
Explanation: The state of motion is described by both the state of rest and motion. There are two types of motion that are uniform and non-uniform motion. When the speed of the object is zero it is said to be at rest but still in the state of motion
12. Answer: (c) electrostatic force
Explanation: When two objects are rubbed together, there is an exchange of electrons. During dry weather, the hair follicles are straightened up and they have picked up electrons during the rubbing process. The follicles have the like charges that repel each other.The force responsible for this is the electrostatic force.
13.Answer: (d) either a magnetic or an electrostatic force
Explanation: Frictional force is applied along the surfaces and depends on contact. hence it is not a repulsive force. Electrostatic and magnetic forces can be either attractive or repulsive. Here, when two objects are experiencing repulsive force because there may be an electrostatic force or a magnetic force.
14. Answer: (c) Force of friction
Explanation: Friction is a surface phenomenon. When two surfaces have irregularities that come in contact they get interlocked preventing them from sliding against each other. So, the frictional force is a contact force dependent on the surface.
15. Answer: (c) Friction
Explanation: When a ball is rolling on ground their is a friction force which retards the motion of ball and make it zero finally.
16. Answer: (d) Opposite to the direction of motion
Explanation: Frictional force offers the resistance to the applied force opposing its motion. Thus, it always acts in the direction opposite to that of the object in motion. If force is applied to the left, then friction acts in the right.
17. Answer: (b) A bar magnet moves a paperclip without touching it
Explanation: A bar magnet moving a paper clip exerts magnetic force of repulsion or attraction and we know that magnetic force is a non contact force in nature.
18. Answer: (c) Attractive force
Explanation: Gravitational force -an attractive force that exists between all objects with mass; an object with mass attracts another object with mass; the magnitude of the force is directly proportional to the masses of the two objects and inversely proportional to the square of the distance between the two objects.
19. Answer: (a) Changes the direction & speed of the ball
Explanation: The correct answer is changes the direction and speed of the ball. A batsman hits the ball for a boundary past the bowler i.e. four runs. The batsman thus changes the direction and speed of the ball. Force can change the state of motion of an object.
20. Answer: (b) decreases
Explanation: When a given force is applied on larger area of contact than the pressure exerted by it decreases.
21. Answer: (c) increases with depth
Explanation: The pressure exerted by a liquid increases with depth.
22. Answer: (b) the pressure inside our bodies is equal to atmospheric pressure
Explanation: The pressure inside our bodies is equal to the atmospheric pressure and cancels the pressure from outside.
23. Answer: (d) either a magnetic or an electrostatic force
Explanation: when two objects are experiencing repulsive force because there may be an electrostatic force or a magnetic force.
24. Answer: (d) Force applied on inflated balloon
Explanation: Force applied on inflated balloon is an example that shows that force can change shape and size of object. Force applied on inflated balloon is an example that shows that force can change shape and size of object.
25. Answer: (b) Inertia
Explanation: Inertia is the tendency of an object to resist changes in its state of motion. The state of motion of an object is defined by its velocity - the speed with a direction.
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