Please select the true statement or the true statements about an object undergoing uniform circular motion.

a$.$ Neither the speed nor the velocity of the object are constant.

b$.$ Both the velocity and the speed of the object are constant.

c$.$ Only the velocity of the object is constant, but not its speed.

d$.$ Only the speed of the object is constant, but not its velocity.

Consider a disk of diameter $d$ rotating about an axis through its centre with angular velocity $$ and experiencing tangential acceleration $a_t.$ Enter below an expression for the angular acceleration $$ of the disk.

$=$

$$

Select below the correct definition of strain if a rod of cross$-$section area $S$ and initially of length $l_0$ has been pulled to the length $l$ using force $F.$

a$.$ Strain is defined as $\frac{F}{S}.$

b$.$ Strain is defined as $\frac{l-l_0}{l}.$

c$.$ Strain is defined as $F(l-l_0).$

d$.$ Strain is defined as $\frac{l-l_0}{l_0}.$

Indicate which of the following statements regarding the microscopic description of ideal gases are correct.

a$.$ All gas molecules move with the same speed if they are at the same temperature.

b$.$ The volume occupied by the gas molecules is negligible in comparison to the total volume in which the gas is contained.

c$.$ The gas molecules are assumed to exert no forces on each other.

d$.$ All the molecules of a gas at a given temperature have the same kinetic energy.

e$.$ The average kinetic energy of an ensemble of gas molecules at a given temperature is proportional to $m^{\frac{1}{2}}.$

A quantity of ideal gas is held in a square box of length $L.$ The measured macroscopic pressure of the gas is $P.$ A gas particle of mass $m$ travelling perpendicular to a wall of the container makes on average $N$ collisions per second with the wall. Assuming that collisions with the wall are elastic and there are no collisions or potential interaction between the atoms, write down an expression for the average kinetic energy per atom.

$\frac{?}{\text{b}\text{a}\text{r}}(E{)}_{\text{k}\text{i}\text{n}}=$