What is kinetic friction and static friction?

1 Answer

Answer :

Friction is the resistance to movement of an object pressing/resting/moving on a surface. It's not intuitively obvious but the standing still friction and moving friction are different. Assume you have a block of wood resting on a tabletop. The amount of force required to make the block begin to move (static friction) is greater than the force required to keep it moving (kinetic friction) after it has begun to move.

Related questions

Description : What is friction? Define coefficient of static friction and coefficient of kinetic friction.

Last Answer : What is friction? Define coefficient of static friction and coefficient of kinetic friction. Give the necessary formula for each.

Description : Friction can be reduced by changing over from _____. A. Sliding to rolling B. Dynamic to static C. Potential energy to kinetic energy D. Rolling to sliding

Last Answer : ANSWER: A

Description : The function of ball bearings in a wheel is – (1) to increase friction (2) to convert kinetic friction into rolling friction (3) to convert static friction into kinetic friction (4) just for convenience

Last Answer : (2) to convert kinetic friction into rolling friction Explanation: A ball bearing is a type of rollingelement bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads.

Description : Kinetic friction is always A. lesser than static friction B. greater than static friction C. equal to static friction D. equal to contact force

Last Answer : lesser than static friction

Description : The function of ball bearings in a wheel is : (1) to increase friction (2) to convert kinetic friction into rolling friction (3) to convert static friction into kinetic friction (4) just for convenience

Last Answer : to convert kinetic friction into rolling friction

Description : Kinetic friction is a.Maximum value of frictional force when a body is about to move b.Friction between two well lubricated bodies c.Friction force acting when the body is in motion d.Driction force which keeps a body in motion e.None of the above

Last Answer : c. Friction force acting when the body is in motion

Description : The maximum frictional force which comes into play when a body just begins to slide over the surface of another body is known as a.Kinetic friction b.Rolling friction c.Dynamic friction d.Limiting friction e.Sliding friction

Last Answer : d. Limiting friction

Description : State the laws of kinetic friction.

Last Answer : State the laws of kinetic friction.

Description : What would cause the force of kinetic friction to increase?

Last Answer : an increase in uk (apex)

Description : A block of mass m is pulled along a surface as shown. The coefficient of kinetic friction between the block and the surface is m and the tension in the rope is T. The acceleration of the block is (a) a = T cos q/mg (b) a = T cos q/mgm (c) a = T cos q/m + mmg (d) None of the above

Last Answer : Ans:(d)

Description : In case of a pipe exit fitted with a nozzle, the (A) Conversion of kinetic head to pressure head is facilitated (B) Conversion of pressure head to kinetic head is facilitated (C) Power transmitted through the nozzle ... in the pipe is equal to one third of the total supply head (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

Description : Tangent of angle of friction is equal to (A) Kinetic friction (B) Limiting friction (C) Angle of repose (D) Coefficient of friction

Last Answer : (D) Coefficient of friction

Description : Kinetic friction is the (A) Tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction (B) Ratio of limiting friction and normal reaction (C) The friction force ... body is just about to move (D) The friction force acting when the body is in motion

Last Answer : (D) The friction force acting when the body is in motion

Description : Ice skating is possible and practical because of a unique property of water. Is it because: w) The coefficient of kinetic friction of steel on frozen water decreases with decreasing temperature x ... sublimes y) The melting point decreases with increasing pressure z) Ice is a good thermal insulator 

Last Answer : ANSWER: Y -- THE MELTING POINT DECREASES WITH INCREASING PRESSURE 

Description : A block of wood initially at rest slides down an inclined plane. Neglecting friction, the kinetic energy of the block at the bottom of the plane is: w) all converted into heat x) equal to its ... kinetic energy at the top of the plane z) dependant on the materials of which the block is made 

Last Answer : ANSWER: X -- EQUAL TO ITS POTENTIAL ENERGY (WITH RESPECT TO THE BOTTOM OF PLANE) WHEN IT WAS AT THE TOP OF THE PLANE.

Description : Kinetic friction is the?

Last Answer : Kinetic friction is the friction force acting when the body is in motion.

Description : Volute of a centrifugal pump should be designed in a fashion, such that the (A) Kinetic head gets converted into static head (B) Moving stream gradually reduces velocity (C) Mean velocity remains constant (D) None of these

Last Answer : (A) Kinetic head gets converted into static head

Description : Design of the casing of centrifugal pump should be such as to minimise the (A) Back flow through impeller (B) Loss of kinetic head (C) Loss of static head (D) None of these

Last Answer : (B) Loss of kinetic head

Description : Good design of the casing of a centrifugal pump aims at minimising the (A) Cavitation (B) Frictional losses (C) Kinetic energy loss (D) Static head

Last Answer : Option C

Description : A uniform cylinder of weight W is rolling while slipping on a rough horizontal surface under the influence of a horizontal force. The force of friction between the cylinder and the surface is a. ... c.Indeterminate d.Determinate but depends on the acceleration of the cylinder e.None of the above

Last Answer : c. Indeterminate

Description : Which one of the following is not the law of dry friction? a.If friction is neglected, the reactions are always normal to the surfaces on contact b.Friction always acts to oppose the relative motion of ... its maximum value d.The force of friction is always normal to the surface e.All of the above

Last Answer : d. The force of friction is always normal to the surface

Description : A 5 m ladder of mass 25 kg is placed in a position where its inclination to a vertical wall is at 30?. A 100 kg man is to climb the ladder. If the coefficient of static friction is 0.25 the height along ladder at which the slipping will be induced would be a.2.4 m b.1.6 m c.0.8 m d.1.2 m e.0.5 m

Last Answer : c. 0.8 m

Description : A uniform cylinder of weight W is rolling while slipping on a rough horizontal surface under the influence of a horizontal force. The force of friction between the cylinder and the surface is a. ... on the acceleration of the cylinder d.107 dynes e.Proportional to the coefficient of static friction

Last Answer : c. Determinate but depends on the acceleration of the cylinder

Description : Static friction is always a.greater than the dynamic driction b.either greater or more than the dynamic friction c.less than the dynamic friction d.107 dynes e.equal to the dynamic friction

Last Answer : a. greater than the dynamic driction

Description : The coefficient of static friction will have the highest value in case of a.Mild steel and mild steel b.Mild steel and copper c.Cast iron and steel d.Rope and wood e.Any of the above loctions

Last Answer : d. Rope and wood

Description : What is Static Friction ?

Last Answer : The friction that occurs between two surfaces when one is not moving relative to the other is called positional friction.

Last Answer : In this friction two objects are subject to each other

Description : A block of mass 37 kg rests on a rough horizontal plane having coefficient of static friction 0.3.

Last Answer : A block of mass 37 kg rests on a rough horizontal plane having coefficient of static friction ... force required to just move the block horizontally.

Description : Calculate the coefficient of static friction for an object of mass 50 kg placed on horizontal table

Last Answer : Calculate the coefficient of static friction for an object of mass 50 kg placed on horizontal ... object just moves when spring balance shows 50N.

Description : State the laws of static friction.

Last Answer : State the laws of static friction.

Description : Why force of static friction is known as ‘self-adjusting force?

Last Answer : Why force of static friction is known as ‘self-adjusting force?

Description : Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head. (A) Manometric (B) Total (C) Static (D) Friction

Last Answer : (A) Manometric

Description : A piezometer provided in the pipe measures (A) Friction factor (B) Static pressure (C) Dynamic pressure (D) None of these

Last Answer : (B) Static pressure

Description : Dynamic friction as compared to static friction is  (A) Same  (B) More  (C) Less  (D) May be less of more depending on nature of surfaces and velocity 

Last Answer : (C) Less 

Description : State four laws of static friction. 

Last Answer : 1. The frictional force is always acts tangential to the plane of contact and in the opposite direction of motion. 2. When the body is in limiting equilibrium, the ratio of limiting friction to ... is a self-adjusting force and it increases as the applied force increases up to limiting friction. 

Description : Dynamic friction as compared to static friction is?

Last Answer : Dynamic  friction  is   less  compared  to  static  friction.