Class 11th

A calorimeter consists of 400g of water at $24°C.$ A 500g piece of copper at $100°C$ is thrown into the water and the equilibrium temperature is found to be $36.5°C.$  What is the molar heat capacity of copper in cal/mol k, given that 1 mol of copper has a mass of 63.5g? Neglect the heat capacity of the container.

A small elastic ball of mass m is placed at the apex of a $45°$  inclined plane as shown in the figure below. The ball is allowed to slip without friction down the plane (along the dotted line), hit the ground (as shown) and bounce along it. If the height of the inclined plane is h and the coefficient of restitution between the ball and the ground is 0.5, then the distance AB, as marked on the figure, will be N * h, where N is

A wave given by equation y = 1mm sin $\left(\frac{nx}{30}-5nt\right)$  is produced in a string 100m long of mass 1 kg. What is the tension (in N) in string? x is in m & t in sec.

A plastic ball is rising in water with terminal speed v. If we use a different plastic whose density is double that of the original ball but still less that density of water, keeping the radius same, the terminal speed would be:

The electric field line pattern for charges + 2q & - q are shown. Select the most appropriate diagram:-

Two blocks of same mass but different density ${\rho }_1\&{\rho }_2$ are floating in water. Block-2 has higher fraction of its volume submerged in water. If buoyant force on them are B₁ & B₂ :-

Assume temperature of 27^oC p = 10⁵ Pa, n = 1 mole diameter of air molecules as 10^-10m, which of the following is correct?

An igloo, a hemispherical enclosure built of ice $\left(1.67J/m-s°C\right)$ , has as inner radius of 2.50m. The thickness of the ice is 0.5m. At what rate must thermal energy be generated to maintain the air inside the igloo at $5°C$ when the outside temperature is - $40°C?$  Ignore all thermal energy losses through the ground or by air currents.

If we want that a simple pendulum oscillates with same time period in summer as it did in winter, what changes to the simple pendulum should we do during summer?