Force

If the block moves towards the right, magnitude of force applied by A is greater than that of B.

The magnetic force is responsible for the movement of hammer. When electric current flows through the coil and the circuit is completed, the magnetic force is produced. As a result, it acts like an electromagnet.

During dry weather, while combing hair, sometimes we experience hair flying apart. The force responsible for this is electrostatic force. The force exerted by a charged body on another charged or uncharged body is known as electrostatic force.

Pressure of water increases with increase in depth. In the given container, C is in depth. Hence, its pressure will be more. Therefore, the correct order is:

Pressure at A< Pressure at B<Pressure at C

When two objects repel each other, this repulsion could be due to either magnetic or an electrostatic force.

In electrostatic force, similar charges may repel each other. In magnetic force, similar poles may repel each other.

When the applied force is in contact with an object, then this is called contact force. Among the given options, force of friction is a contact force because force of friction arises due to contact between surfaces.

Magnetic force, force of gravity and electrostatic force are non-contact forces.

In the given water tank, B and C are at the same levels. Hence, from taps B and C, water will flow out at the same pressure.

The smaller the area, larger the pressure on a surface for the same force. Hence, the brick A whose area of contact is minimum will exert more pressure on the table.

Muscular force is exerted to change the shape of the dough.

The force resulting due to the action of muscles is known as muscular force. When ball of dough is rolled into a flat chapatti, this is caused by the action of muscles in our body. Hence, it is a muscular force.

While walking, we apply force on the ground. The ground applies force on our foot due to which we are able to move. This is called the force of friction.

i. The force of friction always acts on all the moving objects.

ii. Its direction is always opposite to the direction of motion.

Her friend should push the box to the east so that it moves faster in the same direction because:

i. If her friend pushes the box in the east direction, the magnitude of the force increases.

ii. As a result, box will move faster.

The magnetic force causes the deflection because:

i. When the key is closed, the current starts flowing in the wire.

ii. Due to the flowing current, the magnetic field is produced around the circuit.

iii. This exerts a magnetic force on the needle.

iv. As a result, needle gets deflected.

Electrostatic force is responsible for this phenomenon. As we know that electrostatic force is the force exerted by a charged body on another charged or uncharged body. Hence, during dry weather, clothes made of synthetic fiber (uncharged) often stick to the skin (charged).

Gravitational force pulls them down. Objects or things fall towards the earth because it pulls them. This force is called gravitational force. Hence, while sieving grains, small pieces fall down due to the gravitational force of earth.

Yes, the force of gravity act on dust particles.

i. Force of gravity is an attractive force.

ii. It acts on all objects.

iii. The force of gravity acts on all of us all the time without being aware of it.

The upward force is larger than the force of gravity because the balloon is moving upward.

Yes, the force of gravitation exists between two astronauts in space because:

i. Every object in the universe whether small or large exerts a force on every other object.

ii. We can say that this is the universal law of gravitation.

Pressure is defined as the force acting per unit area.

Note that the pressure is inversely proportional to the area. So smaller the area, larger the pressure on a surface.

Chapatti maker works on this principal. This large pressure converts balls of dough into chapattis.

Gravitational force (force of gravity) is the force which is responsible for his downward motion. Whenever any object or thing moves in downward motion or falls towards the earth, the force of gravity takes place.

Now, he will not come down with the same speed without he parachute because the friction of air become less and as a result he will come down with the fastest speed as much as possible.

We infer about the magnitudes and direction of the forces applied that:

i. The magnitude of forces will be equal and same.

ii. The forces will act in the opposite direction.

iii. As a result, they cancel out each other and the net effect will become less.

Electrostatic force is the force which might be responsible for this phenomenon because:

i. Electrostatic force is the force which is produced when charge bodies come together.

ii. It is given that two thermocol balls have similar charges.

iii. As we know that similar charges repel each other.

iv. Hence, they move away from each other due to the repulsion between them.

When fruits detached from a tree fall down due to force of gravity, the objects interacting in this are fruits and earth.

i. As soon as the fruits detached from a tree, earth applies its force of gravity on fruit.

ii. The force of gravity will act towards the centre of the fruit.

iii. Hence, the pull of the earth causes fruits to falls down and interact with the earth.

Men should follow the steps given below:

i. If the force is applied in the direction of opposite to the direction of motion, then it results in a decrease in the speed of the object.

ii. Hence, to slow down the cart, he should apply an opposite force to the moving cart.

iii. To balance the downward motion of cart which is due to the force of gravity, he can start pulling the cart instead of pushing the cart.

Magnetic force in the upward direction and force of gravity in the downward direction acting on the car. Magnetic force is larger than the force of gravity because:

i. The car is sticking to an electromagnet which is lifting the car upwards.

ii. The car is moving upwards.

iii. Hence, magnetic force due to electromagnet is larger than force of gravity.

The initial force that sets the arrow in motion is muscular force:

i. This force is caused by the action of muscles in our body.

ii. The archer stretches his muscles to stretch the string of the bow.

iii. When he releases strings, the shape of the bow changed.

iv. As soon as the string released, the string regains its original position.

v. It provides the initial force to set the arrow in motion.

The arrow ultimately falls down due to force of gravity:

i. The force of gravity always acts in the downward motion.

ii. The arrow ultimately falls towards the earth because earth pulls it.

iii. Force of gravity is an attractive force.

It is difficult to cut cloth using a pair of scissors with blunt blades because:

i. Blunt blades (sharp) have large surface area than that of sharp-edged blades.

ii. As we know that pressure is inversely proportional to the area. Larger the area, smaller will be the pressure.

iii. Hence, in blunt blades, applied force produces very less pressure.

iv. Due to low pressure, this becomes difficult to cut the cloth from blunt blades.

Rod B will sink more because:

i. As we know that the smaller the area, larger the pressure on a surface for the same force applied.

ii. Rod B has a smaller area.

iii. Hence, it will exert more pressure on the sand.

iv. On the other hand, rod A will exert less pressure on the sand as it has a larger area.

The woman wearing sandals with flat soles will feel more comfortable while walking on the sandy beach because:

i. The sandals with flat soles have larger area compared to the pointed heels.

ii. As we know that pressure is inversely proportional to the area.

iii. Hence, larger the area, smaller will be the pressure.

iv. Therefore, the pressure exerted by the sandals having flat soles will be less.

v. On the other hand, the pressure exerted by the pointed heels will be more.

vi. That’s why walking with flat soles will be more comfortable.

It is much easier to burst an inflated balloon with a needle than by a finger because:

i. Pressure is inversely proportional to the area of cross section.

ii. Hence, smaller the area, larger will be the pressure.

iii. Needle has a smaller area of contact compared to the finger.

iv. Thus, needle will exert more pressure on the balloon.

v. Larger pressure by needle burst an inflated balloon.

Order of deceasing pressure at the base of each vessel is:

Pressure of D > Pressure of B > Pressure of A > Pressure of C

Pressure depends upon the height of the liquid. Larger the height of the fluid is, larger will be the pressure at the base. Hence, vessel D will exert more pressure at the base in comparison to others.

D (60mL) > B (50mL) > A (300 mL) > C (500 mL)

Note: Pressure does not depend upon the volume of the liquid. Pressure depends upon three things which are:

i. Gravitational force

ii. Density of liquid

iii. Height of liquid