BioMedical Admissions Test (BMAT) Section 2: Scientific Knowledge and Applications — Physics Syllabus

Define speed and velocity, noting the key difference.

Speed is distance travelled per unit time (scalar); velocity is displacement per unit time (vector, has direction): $v = \frac{\Delta s}{\Delta t}$.

Define acceleration and give its formula and unit.

Acceleration is the rate of change of velocity: $a = \frac{\Delta v}{\Delta t}$. Unit is $\text{m s}^{-2}$.

State the four SUVAT equations of motion for uniform acceleration.

$v = u + at$;\quad $s = ut + \frac{1}{2}at^{2}$;\quad $v^{2} = u^{2} + 2as$;\quad $s = \frac{(u+v)}{2}t$.

What does the gradient of a distance–time graph represent?

The gradient equals speed (or velocity). A curved line indicates acceleration; a steeper line means a greater speed.

What do the gradient and area under a velocity–time graph represent?

The gradient gives acceleration; the area under the graph gives the displacement (distance travelled).

State the value and direction of gravitational acceleration near Earth's surface.

$g \approx 9.8\,\text{m s}^{-2}$ (often taken as $10\,\text{m s}^{-2}$), directed vertically downwards.

State Newton's first law of motion.

A body remains at rest or moves at constant velocity unless acted on by a resultant (net) external force.

State Newton's second law as an equation and define the terms.

$F = ma$, where $F$ is the resultant force (N), $m$ is mass (kg) and $a$ is acceleration ($\text{m s}^{-2}$).

State Newton's third law of motion.

When body A exerts a force on body B, body B exerts an equal and opposite force on body A (the forces act on different objects).

What is the difference between mass and weight, including the formula linking them?

Mass (kg) is the amount of matter and is constant; weight (N) is the gravitational force on it: $W = mg$, which varies with $g$.

Define momentum and give its formula and unit.

Momentum is mass times velocity: $p = mv$ (a vector). Unit is $\text{kg m s}^{-1}$ (or $\text{N s}$).

State the principle of conservation of momentum.

In a closed system with no external resultant force, total momentum before a collision equals total momentum after: $\sum p_{\text{before}} = \sum p_{\text{after}}$.

How is resultant force related to rate of change of momentum?

$F = \frac{\Delta p}{\Delta t} = \frac{m\Delta v}{\Delta t}$. This is the more general form of Newton's second law; impulse $= F\,t = \Delta p$.

Define the moment of a force and give its formula and unit.

A moment is the turning effect of a force: $\text{moment} = F \times d$, where $d$ is the perpendicular distance from the pivot to the line of action. Unit is $\text{N m}$.

State the principle of moments for an object in equilibrium.

For a body in rotational equilibrium, the sum of clockwise moments about any pivot equals the sum of anticlockwise moments.

Define pressure and give its formula and SI unit.

Pressure is force per unit area: $P = \frac{F}{A}$. SI unit is the pascal (Pa), where $1\,\text{Pa} = 1\,\text{N m}^{-2}$.

State the formula for pressure in a column of fluid (hydrostatic pressure).

$P = \rho g h$, where $\rho$ is fluid density ($\text{kg m}^{-3}$), $g$ is gravitational field strength and $h$ is depth.

Define work done and give its formula and unit.

Work done is force times distance moved in the direction of the force: $W = Fd$. Unit is the joule (J), where $1\,\text{J} = 1\,\text{N m}$.

Give the formulae for kinetic energy and gravitational potential energy.

$E_k = \frac{1}{2}mv^{2}$ and $E_p = mgh$.

State the principle of conservation of energy.

Energy cannot be created or destroyed, only transferred from one store to another; the total energy in a closed system remains constant.

Define power in terms of energy and work, with two formulae.

Power is the rate of doing work or transferring energy: $P = \frac{W}{t} = \frac{E}{t}$. It also equals $P = Fv$. Unit is the watt (W).

How is efficiency calculated?

$\text{efficiency} = \frac{\text{useful energy (or power) output}}{\text{total energy (or power) input}} \times 100\%$.

Define wavelength, frequency and amplitude of a wave.

Wavelength ($\lambda$) is the distance between adjacent identical points; frequency ($f$) is the number of waves per second (Hz); amplitude is the maximum displacement from the rest position.

State the wave equation linking speed, frequency and wavelength.

$v = f\lambda$, where $v$ is wave speed ($\text{m s}^{-1}$), $f$ is frequency (Hz) and $\lambda$ is wavelength (m).

Distinguish between transverse and longitudinal waves, giving an example of each.

In transverse waves oscillations are perpendicular to energy travel (e.g. light, water waves); in longitudinal waves oscillations are parallel, forming compressions and rarefactions (e.g. sound).

Name the three types of nuclear radiation in order of increasing penetrating power, and their nature.

Alpha ($\alpha$, a helium nucleus $^{4}_{2}\text{He}$) — stopped by paper; beta ($\beta$, a fast electron) — stopped by aluminium; gamma ($\gamma$, electromagnetic radiation) — reduced by thick lead.

Write the change in mass and atomic number for alpha and beta-minus decay.

Alpha decay: mass number $-4$, atomic number $-2$. Beta-minus decay: mass number unchanged, atomic number $+1$ (a neutron becomes a proton plus an emitted electron).

Define the half-life of a radioactive isotope.

The half-life is the average time taken for half the radioactive nuclei in a sample to decay, or for the activity (count rate) to fall to half its initial value.

Rearrange $v^{2} = u^{2} + 2as$ to make $a$ the subject.

$a = \frac{v^{2} - u^{2}}{2s}$.

Express $0.00045$ and $6\,200\,000$ in standard form.

$0.00045 = 4.5 \times 10^{-4}$ and $6\,200\,000 = 6.2 \times 10^{6}$.

How do you determine the gradient and intercept of a straight-line graph, and what does the equation $y = mx + c$ represent?

Gradient $m = \frac{\Delta y}{\Delta x}$ (rise over run between two points); $c$ is the $y$-intercept where the line crosses the $y$-axis. The line shows a linear (proportional if $c=0$) relationship between the variables.