# Physics - Misc

When is terminal velocity reached?

When the resultant force on a falling object is zero.

What’s the formula for percentage difference?

What’s an alternative to the words more/less or goes up/down in Physics?

Increases.

What’s an alternative to the phrase “balanced forces”?

Net force or resultant force is zero.

What is the centre of gravity?

The point on an object at which the entire weight of the object may be considered to act.

What is the centre of mass?

The point on an object at which mass can be considered to be concentrated.

When can the centre of mass be different to the centre of gravity?

If the object in question is not in a uniform gravitiational field.

When asked to critique an experiment, what should you look at first?

The sources of uncertainty.

What is a disadvantage of wind power over tidal power?

Wind power requires wind to function.

What is the differential of $s = \frac{1}{2}at^2$?

### 2020-12-10

If you travel faster than the speed of waves caused by walking through water, what happens to the water in front of you?

It builds up in amplitude.

### 2021-01-18

Which is heavier, a proton or an electron?

A proton.

What is the mass of an electron?

What is the speed of light?

### 2021-01-21

What additional piece of equipment do you need alongside light gates?

A datalogger.

### 2022-03-07

When justifying a statement with a proportionality relationship (e.g. “this holds true because force is proportional to mass”), what must you also specify?

That the other variables in the proportionality relationship are held constant.

### 2022-05-19

“Write an expression for the gravitational potential $V _ g$ at the surface of a planet of mass $M$ and radius $r$”?

What is it important you remember when quoting gravitational or electric potential equations?

The minus sign.

What’s the other equation that should come to mind apart from $n\lambda = d\sin\theta$?

### 2022-05-20

What is accuracy?

The closeness of agreement between an experimental result and the true value.

What is precision?

The closeness of agreement between independent measurements under the same conditions.

### 2022-05-21

What has to be true about best and worst fit lines?

They have to pass through all the error bars.

Why might it not be required to put error bars on a graph?

Because the error is very small.

When a question asks you to find the gradient and then calculate something (e.g. calculate the gradient, then find the force constant) what must you be careful about?

Whether you need to manipulate the gradient first (e.g. reciprocal).

### 2022-05-22

What is the formula for percentage uncertainty?

### 2022-06-08

Given a graph of one variable against another, what test could you do to see if one of them was inversely proportional to the other?

See if pairs of values multiplied together equal a constant.

### 2022-06-12

How can you increase the accuracy of measured values of wavelength by looking at higher-order maxima?

The uncertainty in your measurements will be the same, but the angle is bigger and so there is a smaller percentage uncertainty.