Physics: Forces and Motion Practice Flashcards

Practice flashcards covering motion equations, graph interpretation, Newton's laws, Hooke's law, moments, and momentum based on GCSE Physics standards.

How is average speed calculated?

$$\text{average speed} = \frac{\text{total distance}}{\text{total time}}$$

What is the formula for acceleration using initial velocity ($u$), final velocity ($v$), and time taken ($t$)?

$$a = \frac{v-u}{t}$$

Which equation relates final speed ($v$), initial speed ($u$), acceleration ($a$), and distance ($s$)?

$$v^2 = u^2 + 2as$$

In a displacement-time graph, what physical quantity does the gradient represent?

Velocity

In a velocity-time graph, what does the area under the line represent?

The distance travelled

In a velocity-time graph, what does a horizontal line indicate?

Constant speed

What is the difference between a scalar and a vector quantity?

A vector has magnitude and direction, while a scalar has only magnitude.

Give three examples of vector quantities identified in the notes.

Displacement, Velocity, Acceleration, and Force

How is the resultant force calculated for two forces acting in opposite directions along the same line?

They should be subtracted from each other.

State Newton’s second law in the form of an equation.

$F = ma$ (where force equals mass multiplied by acceleration)

What is the difference between mass and weight?

Mass is a measure of how much matter is in an object ($kg$), while weight is a gravitational force ($N$) resulting from a gravitational field acting on a mass.

What is the formula to calculate weight ($W$)?

$W = mg$, where $m$ is mass and $g$ is gravitational field strength.

What is the value of the gravitational field strength on Earth according to the notes?

$$10\,N/kg$$

Describe the state of a falling object when it reaches terminal velocity.

The weight and air resistance are equal and opposite, resulting in no resultant force and zero acceleration.

What is 'thinking distance'?

The distance travelled in the time between the driver realising he needs to brake and actually pressing the brakes.

How is the total stopping distance of a vehicle calculated?

$$\text{stopping distance} = \text{thinking distance} + \text{braking distance}$$

Define 'elastic deformation'.

Elastic deformation is when an object returns to its original shape once the load has been removed.

What is Hooke’s law equation for a spring?

$F = kx$, where $F$ is the force applied, $k$ is the spring constant, and $x$ is the extension.

What does the 'limit of proportionality' represent on a force-extension graph?

The point where the object stops being linear and no longer obeys Hooke’s law.

How is the moment of a force calculated?

$\text{moment} = \text{force} \times \text{perpendicular distance from the pivot}$ ($moment = Fd$)

What is the Principle of Moments regarding an object in equilibrium?

The sum of clockwise moments equals the sum of anticlockwise moments.

What is the formula and unit for momentum ($p$)?

$p = mv$; measured in kilogram metres per second ($kgm/s$).

How is force related to the change in momentum?

$F = \frac{mv-mu}{t}$ (force equals change in momentum divided by time taken)

Explain how car safety features like seatbelts protect passengers using the concept of momentum.

They increase the time taken for the people to come to rest, which reduces the force for the same change in momentum.

What does the principle of the conservation of momentum state?

In a collision, the total momentum before the event is equal to the total momentum afterwards.