List of practice Questions

A body of mass $m$ moving with velocity $v$ makes a head-on collision with another body of mass $2\, m$ which is initially at rest. The loss of kinetic energy of the colliding body (mass $m$ ) is

When a wire is stretched and its radius becomes $\frac {r}{2}$. then its resistance will be

A copper wire of length $1\, m$ and radius $1\, mm$ is joined in series with an iron wire of length $2\, m$ and radius $3\, mm$ and a current is passed through the wires. The ratio of the current density in the copper and iron wires is

A cane filled with water is revolved in a vertical circle of radius $4\, m$ and the water does not fall down. What must be the maximum period of revolution?

A block of mass $m$ is connected to another block of mass $M$ by a spring (massless) of spring constant $k$. The blocks are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is unstretched. Then a constant force $F$ starts acting on the block of mass $M$ to pull it. Find the force on the block of mass $m$

Menstrual flow occurs due to lack of

A meristenatic region present between xylem and phloem of open vascular bundle is called

Bulliform cells are found in

A long straight wire of radius $'a'$ caries a steady current $i$. The current across its cross section. The ratio of the magnetic field at $\frac{a}{2}$ and $2a$ is

An ideal coil of $10H$ is connected in series with a resistance of $5\, \Omega$ and a battery of $5V. 2$ second after the connection is made the current flowing in amperes in the circuit is

For inelastic collision between two spherical rigid bodies

A point initially at rest moves along $x$-axis. Its acceleration varies with time as $ a=(6t+5)\,m/s^{2}$ . If it starts from origin, the distance covered in $2\, s$ is

A point source emits sound equally in all directions in a non-absorbing medium. Two points $P$ and $Q$ are at distances of $2\, m$ and $3\, m$ respectively from the source. The ratio of the intensities of the waves at $P$ and $Q$ is

Which of the following expressions is that of a simple harmonic progressive wave?

A solid sphere rolls down on two different inclined planes of same height, but of different inclinations. In both cases

Use of eddy currents is done in the following except

Two equal drops of water are falling through air with a steady velocity $v$. If the drops coalesced what will be the new velocity?

Two friends $A$ and $B$ are waiting for another friend for tea. A took the tea in a cup and mixed the cold milk and then waits. B took the tea in the cup and then mixed the cold milk when the friend comes. Then the tea will be hotter in the cup of

A good lubricant should have

The path of an electron in a uniform magnetic field may be

A magnetic needle is placed on a cork floating in a still lake in the northern hemisphere. Does the needle together with the cork move towards the north of the lake?

A $60 \,kg$ man stands on a spring scale in the lift. At some instant he finds, scale reading has changed from $60 \,kg$ to $50 \,kg$ for a while and then comes back to the original mark. What should we conclude?

Identify the incorrect statement among the following

The cell, $Zn\left|Zn^{2+}\left(1M\right)\right|\left|Cu^{2+}\left(1M\right)\right|Cu\left(E^{0}_{cell}=1.10V\right), $ was allowed to be completely discharged at $298 \,K$. The relative concentration of $Zn^{2+} to Cu^{2+}\left[\frac{\left[Zn^{2+}\right]}{\left[Cu^{2+}\right]}\right]$ is

Which one of the following has a square planar geometry (At nos.: Fe = 26, Co = 27, Ni = 28, Pt = 78)