$10,000$ small balls,each of mass $1 \, g$,strike a surface of area $1 \, cm^2$ per second with a velocity of $100 \, m/s$ perpendicular to the surface. They rebound with the same velocity. What is the pressure exerted on the surface?

Consider an engine that absorbs $130 \text{ cal}$ of heat from a hot reservoir and delivers $30 \text{ cal}$ of heat to a cold reservoir in each cycle. The engine also consumes $2 \text{ J}$ of energy in each cycle to overcome friction. If the engine works at $90 \text{ cycles per minute}$, what will be the maximum power delivered to the load (in $\text{ W}$)? [Assume the thermal equivalent of heat is $4.2 \text{ J/cal}$]

Heat is applied to a rigid diatomic gas at constant pressure. The ratio $\Delta Q : \Delta U : \Delta W$ is

Helium gas undergoes a cycle $ABCDA$ (consisting of two isochoric and two isobaric lines) as shown in the figure. The efficiency of this cycle is nearly ....... $\%$ (Assume the gas to be an ideal gas).

Write the equation for the work done during the compression of an ideal gas.

An ideal gas undergoes a cyclic process through various thermodynamic states. The heat energy $(Q)$ and work $(W)$ associated with these states are given as follows:
$Q_1 = 6000 \ J, Q_2 = -5500 \ J, Q_3 = -3300 \ J, Q_4 = 3500 \ J,$
$W_1 = 2500 \ J, W_2 = -1000 \ J, W_3 = -1200 \ J, W_4 = x \ J$
If the ratio of the net work done to the net heat absorbed is $\eta$, then the values of $x$ and $\eta$ are respectively: