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Which of the following is/are the unit(s) of density?

While connecting a bulb to a battery, one of the terminals of the battery was left disconnected. Pick the correct statement.

A block of weight $100$ N is suspended by copper and steel wires of same cross sectional area $0.5c{m}^2$ and length $\sqrt{3}m$ and $1m$ respectively. Their other ends are fixed on a ceiling as shown in figure. The angles subtended by copper and steel wires with ceiling are ${30}^o$ and ${60}^o$ respectively. If elongation in copper wire is $\Delta l_C$ and elongation in steel wire is $\Delta l_S$, then the ratio $\frac{\Delta l_C}{\Delta l_S}$ is

(Young's modulus for copper and steel are $1\times {10}^{11}N/m^2$ and $2\times {10}^{11}N/m^2$ respectively)

Most of the electricity-carrying wires along the roads do not have a plastic covering like the wires used at homes. Why?

Match the following.

1. 7

A cab driver picks 1st passenger who is 0.8 km away and then he picks another passenger who is 0.5 km away from the first passenger. Then drops the 1st passenger to a place that is 2 km away from the second pick up point and drops the 2nd passenger to a place 1.7 km away from the place where he dropped the 1st passenger. If the average speed throughout the journey is 40 kmph, find out the time taken to complete the whole journey.

A particle had a velocity of $18m/s$ in the right direction and $2.4s$ later its velocity was $30m/s$ in the opposite direction. What was the acceleration of the particle during this $2.4s$ interval?

Question 10

To keep her soup warm, Paheli wrapped the container, in which it was kept with a woollen cloth. Can she apply the same method to keep a glass of cold drink cool? Give reason for your answer.

Mass of two spheres are in the ratio 8:1. Assuming that both of them have the same density, find the ratio of their radii.

Choose the options for abstract characteristics of Ratio :

Weight of an object is:

The distance vs time graph of a car is given below. What is the time the car takes to cover a distance of 4 km?

Question 3 (c)
State whether the following statement is true or false.
If the amplitude of vibration is large, the sound is feeble.

The stress Vs strain graph, for wires of two materials A and B, are as shown in the figure. If ${\gamma }_A$ and ${\gamma }_B$ are the Young's moduli of the two materials, then,

Why is tungsten wire used for making filaments

Vijay is pulling a block with 22 N force and Gopal is pulling it with 10 N force in opposite direction. Vijay is able to pull the block a total distance of 6.5 m. Find the net work done by the two forces.

Question 6

When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.

1. 757.58

When we change the direction of current in a conductor, the magnetic field line around it

​What will happen if the person in our example, who picks up balls from below and puts it on top of the C-shaped tube, stops doing his job?

Consider an expanding sphere of instantaneous radius $R$ whose total mass remains constant. The expansion is such that the instantaneous density $\rho$ remains uniform throughout the volume. The rate of fractional change in density $\left(\frac{1}{\rho }\frac{d\rho }{dt}\right)$ is constant. The velocity $v$ of any point on the surface of the expanding sphere is proportional to

Sushweta has to send a laser signal to Garima. But she finds out that the signal misses Garima by $4^0$. She asks Himanshu to rotate the mirror.

By what angle should Himanshu rotate the mirror so that the signal reaches to Garima?