Science M.C.Q. [I MARKS]

Because rolling friction allows to move heavier objects from one place to other easily.

Among the given surfaces, the towel offers the greatest frictional resistance to the rolling of the ball over it. A towel is made up of cotton threads that offer a great amount of resistance, i.e., frictional force, to any motion over their surface. As the ball rolls down and moves on the towel, it stops quickly after travelling the shortest distance. This is because the friction offered by the towel surface to the moving ball is the greatest among the given surfaces.

Friction is generated due to the interlocking of irregularities of two surfaces placed in contact. A decrease in irregularities results in the smoothness of the surfaces and hence smooth movement of the surfaces related to each other. Oil has the maximum tendency to reduce the irregularities between the two contact surfaces. When Amit rubs his hands with oil, the friction between his palm and the tumbler surface is reduced. This makes it difficult for Amit to grip it properly by his hands. Hence, he would require more effort to grip it in this case.

Friction is caused by the interlocking of irregularities in the surfaces of the two objects which are in contact with each other. Sliding friction is between two objects when one or both are sliding against each other. In this case, the book is sliding down the titled table. So, the motion is directed downwards. So, the friction will act on the book in the direction opposite to movement. So, friction will act upwards. Sliding friction is less than static friction, so when the table is titled, the book starts to slide.

Talcum powder is used to reduce friction on the carom board. The powder particles help create a smooth layer over the board?s surface. Thus, talcum powder reduces the roughness of the board. As a result, the carom men and striker can slide easily on the board.

Friction is force that only occurs when an object moves. The force of friction acts in the direction opposite to the direction of motion of an object.

Leaves falling from a tree onto the ground is due to the effect of gravitational force and not due to frictional force.

Force of friction depends on the mass of the object.

As the roughness of the surface increases, the friction increases.

Friction due to air is much smaller than the friction due to liquid.

As the roughness of the surface increases, the friction force increases.

Friction can be minimized but cannot reduced to zero.

The frictional force exerted by fluids is called drag.

Since, rolling friction is less than sliding friction, the tyres are made circular instead of flat.

The use of ball bearings causes rolling friction which is much less than the sliding friction.

We know that friction force acts in an opposite direction to the direction in which an object moves. The maximum frictional force present between two objects is static friction. And sliding friction is smaller than static friction. And rolling friction is much less than sliding friction.

The roughness over a surface increases its friction. Sparks are produced when a matchstick is rubbed against the rough surface of a matchbox. This is caused by the large friction produced between the matchstick and the box. Hence, the sides of matchboxes are made rough.

Friction is the relative force between two surfaces in contact, which causes the decrease in the movement of a body or sometimes may even prevent the motion.

The friction between two surfaces always opposes the relative motion of the surfaces. When the ball moves upward along the inclined plane, frictional force acts downward. Similarly, when the ball rolls down, the force of friction acts upward. In both the cases, friction opposes the motion of the ball, as shown in the given figure.

The book starts sliding down slowly sliding slowly, because the sliding friction is less than force of gravity.

Mustard oil reduces the friction on his hands. So, glass tumbler will be most difficult to handle. Rest of all have much irregularities to hold. And glass has very smooth surface.

Force of friction has many disadvantages associated with it. For example, the friction between the tyres of cars and the road generates heat. This heat causes the heating up of the tyres. As a result of this, tyres get worn out soon.

Friction is a type of contact force that always acts in the direction opposite to the direction of motion. This property of friction is used in the braking system of bicycles and other vehicles to stop the same. The braking system of a cycle consists of brake pads and tyres. These pads do not touch the tyres while the bicycle moves smoothly. But as the brakes are applied, these pads come in contact with the moving tyres. As a result, friction is generated in the opposite direction that tend to stop the motion of the tyres and hence the motion of the bicycle. Depending on the contact area, the magnitude of friction varies. In the given situation, the cyclist applies the brake firmly and hence, a large amount of friction is generated in between the pads and the tyres that eventually stop the cycle.

The frictional force exerted by fluids is called drag force.

The fluid friction can be reduced or minimized by giving special shape called “streamlined shape”. They have a special shape. Aeroplane, rockets, birds, fish, car have streamlined shape. But, bus has no streamlined shape.

Friction plays an important role in the striking of a match stick, playing snooker and writing on the black board.

Frictional force is the opposing force acting in case of ball moving. This cause, the ball to stop after a while.

Friction opposes the relative motion of objects. In its absence, a moving object will not stop.