MCQ
A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically upwards with a velocity $4\,m s ^{-1}$. The ball strikes the water surface after $4\,s$. The height of bridge above water surface is $......\,m$ $\left(\right.$ Take $\left.g=10\,m s ^{-2}\right)$
  • A
    $68$
  • B
    $56$
  • C
    $60$
  • $64$

Answer

Correct option: D.
$64$
d
$S = ut +\frac{1}{2} a t^2$

$-H =4 \times 4-\frac{1}{2} \times 10 \times 4^2$

$-H =16-80$

$-H =-64$

$H =64\,m$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

A semiconductor dopped with a donor impurity is
$A, \,B$ and $C$ are voltmeters of resistance $R, \,1 .5R$ and $3R$ respectively as shown in the figure. When some potential difference is applied between $X$ and $Y,$ the voltmeter readings are $V_A, \,V_B$ and $V_C$ respectively. Then
A rod $(AB)$ is attached to a fixed point $(C)$ using a light rope $(AC)$. The other end of the rod $(B)$ is sitting on ice with negligible friction and the system is in stationary position. Which of the following can be the equilibrium configuration of this system?
If the dimensions of length are expressed as ${G^x}{c^y}{h^z}$; where $G,\,c$ and $h$ are the universal gravitational constant, speed of light and Planck's constant respectively, then
A current carrying infinitely long wire is kept along the diameter of a circular wire loop, without touching it. The correct statement $(s)$ is (are) :

$(A)$ the emf induced in the loop is zero if the current is constant.

$(B)$ The emf induced in the loop is finite if the current is constant.

$(C)$ The emf induced in the loop is zero if the current decreases at a steady rate.

$(D)$ Theemf induced in the loop is finite if the current decreases at a steady rate.

A parallel plate condenser has a capacitance $50\,\mu F$ in air and $110\,\mu F$ when immersed in an oil. The dielectric constant $'k'$ of the oil is
In which of the following series, does the $121.5\,n m$ line of the spectrum of the hydrogen atom lie?
A thin wire of length $2\,m$ is placed perpendicular to the $x-y$ plane. It is moved with velocity $\overrightarrow v  = \left( {2\hat i + 3\hat j + \hat k} \right)\,m/s$ through a region of magnetic induction $\overrightarrow B  = \left( {\hat i + 2\hat j} \right)\,wb/{m^2} .$ The potential difference induced between the ends of the wire is......$volts$
 An electric dipole is placed at an angle of $30^o $ with an electric field intensity $2 \times \,\,10^5 \,\,NC^{-1}$ It experiences a torque equal to $4\,\, N m.$ The charge on the dipole, if the dipole length is $2\,\, cm,$ is
A cylindrical tube of cross-sectional area $A$ has two air tight frictionless pistons at its two ends. The pistons are tied with a straight two ends. The pistons are tied with a straight piece of metallic wire. The tube contains a gas at atmospheric pressure $P_0$ and temperature $T_0$. If temperature of the gas is doubled then the tension in the wire is