Home
Class 12
PHYSICS
Assertion:- A ball allowed to spin in a ...

Assertion:- A ball allowed to spin in a region of uniform wind motion, will get an uplift.
Reason:- Due to spin of the ball in a region of uniform wind motion, the difference in velocity of air flow is present between the lower and upper position of ball, leading to varying pressure.

A

If both Assertion `&` Reason are True `&` the Reason is a correct explanation of the Assertion.

B

If both Assertion `&` Reason are True but Reason is not a correct explanation of the Assertion.

C

If Assertion is True but the Reason is False.

D

If both Assertion `&` Reason are False.

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Topper's Solved these Questions

  • TEST PAPERS

    ALLEN|Exercise PAPER 2|60 Videos
  • TEST PAPERS

    ALLEN|Exercise PAPER 3|99 Videos
  • TEST PAPER 4

    ALLEN|Exercise PHYSICS|44 Videos
  • UNIT & DIMENSIONS, BASIC MATHS AND VECTOR

    ALLEN|Exercise Exercise (J-A)|7 Videos

Similar Questions

Explore conceptually related problems

Statement-1: As wind flows left to right and a ball is spined as shown, there will be a lift of the ball. Statement-2: Decrease in velocity of air below the ball, increases the pressure more than that above the ball.

A ball of mass m with a charge q can rotate in a vertical plane at the end of a string of length l in a uniform electrostatic field whose lines of force are directed upwards. What horizontal velocity must be imparted to the ball in the upper position so that the tension in the string in the lower position of the ball is 1.5 times than the weight of the ball?

Assertion A ball tied by thread is undergoing circular motion (of radius R) in a vertical plane. (Thread always remains in vertical plane). The difference of maximum and minimum tension in thread is independent of speed (u) of ball at the lowest position (ugtsqrt(5gR)) . Reason For a ball of mass m tied by thread undergoing vertical circular motion (of radius R), difference in maximum and minimum magnitude of centripetal aceleraion of the ball is independent of speed (u) of ball at the lowest position (ugrsqrt5gR)) .

A small ball of mass m and charge q is attached to the bottom end of a piece of negligible mass thread of length l, whose top end is fixed. The system formed by the thread and ball is in vertical plane and is in uniform horizontal magnetic field B, which is perpendicular to the plane of figure and points into the paper The ball is started with a velocity v_(0) from lower most point of circle in a direction perpendicular both to the magnetic induction and to direction of thread. The ball moves along a circular path such that thread remains tight during the whole motion. Neglect any loss of enery. What is the magnitude of magnetic induction B, if the minimum initial speed at which the described motion of ball (complete vertical circular motion) occurs is V_(0)=(1)/(2)sqrt(17gL)

Assertion If a charged particle is pronected in a region, where B is perpendicular to velocity of projection, then the net force acting on the particle is independent orf its mass. Reason The particle is performing uniform circular motion and force acting on it is (mv^(2))/(r) .

A small ball of mass m and charge q is attached to the bottom end of a piece of negligible mass thread of length l, whose top end is fixed. The system formed by the thread and ball is in vertical plane and is in uniform horizontal magnetic field B, which is perpendicular to the plane of figure and points into the paper The ball is started with a velocity v_(0) from lower most point of circle in a direction perpendicular both to the magnetic induction and to direction of thread. The ball moves along a circular path such that thread remains tight during the whole motion. Neglect any loss of enery. Choose CORRECT statement

There is an insulator rod of length L and of negligible mass with two small balls of mass m and electric charge Q attached to its ends. The rod can rotate in the horizontal plane around a vertical axis crossing it ata distance L//4 from one of its ends. At first the rod is in unstabele equillbrium in a Horizontal uniform electric field of field strenght E. Then we gently displace it from this position. Determine the maximim velocity attained by the ball taht is closer to the axis in the subsequent motion

A uniform ball of radius r is placed on the top of a sphere of radius R = 10 r. It is given a slight push due to which it starts rolling down the sphere without slipping. The spin angular velocity of the ball when it breaks off from the sphere is omega=sqrt((p)/(q)((g)/(r))) , where g is the acceleration due to gravity and p and q are the smallest integers. What is the value of p+q ?

When a viscous liquid flows , adjacent layers oppose their relative motion by applying a viscous force given by F = - eta A (dv)/(dz) where , ete = coefficient of viscosity , A = surface area of adjacent layers in contact , (dv)/(dz) = velocity gradient Now , a viscous liquid having coefficient of viscosity eta is flowing through a fixed tube of length l and radius R under a pressure difference P between the two ends of the tube . Now consider a cylindrical vloume of liquid of radius r . Due to steady flow , net force on the liquid in cylindrical volume should be zero . - eta 2pirl (dv)/(dr) = Ppir^(2) - int _(v)^(0),dv = P/(2 eta l) int_(tau)^(R) rdr ( :' layer in contact with the tube is stationary ) v = v_(0) (1- (r^(2))/(R^(2))) , where v_(0) = (PR^(2))/(4nl) :. " " Q = (piPR^(4))/(8etaL) This is called Poisecuille's equation . The viscous force on the cylindrical volume of the liquid varies as

In a metal in the solid state, such as a copper wire, the atoms are strongly bound to one another and occupý fixed positions. Some electrons (called the conductor electrons) are free to move in the body of the metal while the other are strongly bound to their atoms. In good conductors, the number of free electrons is very large of the order of 10^(28) electrons per cubic metre in copper. The free electrons are in random motion and keep colliding with atoms. At room temperature, they move with velocities of the order of 10^5 m/s. These velocities are completely random and there is not net flow of charge in any directions. If a potential difference is maintained between the ends of the metal wire (by connecting it across a battery), an electric field is set up which accelerates the free electrons: These accelerated electrons frequently collide with the atoms of the conductor, as a result, they acquire a constant speed called the drift speed which is given by V_e = 1/enA where I = current in the conductor due to drifting electrons, e = charge of electron, n = number of free electrons per unit volume of the conductor and A = area of cross-section of the conductor. A uniform wire of length 2.0 m and cross-sectional area 10^(-7) m^(2) carries a current of 1.6 A. If there are 10^(28) free electrons per m in copper, the drift speed of electrons in copper is