Forces

Speed

a scalar quantity defining how fast an object moves, measured as the rate of change in distance.

Distance

a scalar quantity of far something travels.

Displacement

How far something travels in a given direction.

Acceleration

The rate of change in velocity.

Scalar

A quantity with magnitude.

Vector

A quantity with magnitude and direction.

Velocity

How fast something travels in a given direction.

label the displacement graph

in a displacement time graph, what does positive gradient represent

moving forwards

in a displacement time graph, what does negative gradient represent

moving backwards

in a displacement time graph, what does straight line represent

constant velocity

in a displacement time graph, what does curved line represent

accelerating or decelerating

in a displacement time graph, what does horizontal line represent

stationary

in a displacement time graph, what does line touching x axis represent

object back at origin

label the velocity time graph

A= Constant acceleration
B= Constant velocity

C= Constant deceleration

D= Stationary

What does SUVAT stand for

Displacement, Initial velocity, Final velocity, Acceleration, Time

displacement unit

m

initial velocity unit

m/s or ms^-1

final velocity

m/s or ms^-1

acceleration unit

m/s² or ms^-2

time unit

s

SUVAT Equations

1. v= u+ at

2. s= ut+ ½ at²

3. s= ½ (u+v) t

4. v² = u² + 2as

The gradient of a displacement - time graph is what

velocity

The gradient of a velocity-time graph is what

Acceleration

The area under a velocity-time graph is what

displacement

how to use two light gates

1. Set up the ramp with two light gates (attached to a computer) at the bottom

2. Measure the length of the card using a ruler

3. Release the trolley from rest at the top of the ramp.

4. As the trolley passes through light gate 1 and 2, times t₁ and t₂ are recorded, on the data logger, as the card blocks the light beam. 

5. The time for the trolley to pass between the light gates is also recorded. 

using one light gate

1. Set up the ramp (attached to 2 masks) with one light gate (attached to a computer) at any point

2. Measure the length of each mask using a ruler, ideally, these should be the same length. 

3. Release the trolley from rest at the top of the ramp.

4. As the trolley passes the light gate, the computer records the time t₁ that the first card blocks the light beam and the time t₂ that the second card blocks the light beam. 

how to find the acceleration of the trolley without light gates and a datalogger

1. Draw two lines across a tilted board, one near the top and one near the bottom.

2. Measure the distance between both lines.

3. Hold the trolley so it is lined up with the first line.

4. Let go, and simultaneously start the stopwatch. Stop the stopwatch just as the front of the trolley meets the bottom line.

5. use s = ut+ ½ at²

What is drag?

the frictional force that opposes the movement of an object through a gas or a liquid. eg - air resistance

resultant force

the combined effect of multiple forces acting on the same object.

how is the resultant force calculated

• subtracting opposite forces from one another.

• If the resultant force is 0 N we say the forces are balanced. 

• If the resultant force is greater than 0N, the object will accelerate in the direction with a larger magnitude

What is a free-body diagram?

A diagram showing all the forces acting on a single object, represented by arrows pointing in the direction of each force.

What are the common forces shown in free-body diagrams?

• Weight (W): Force due to gravity, points down

• Normal force (N): Contact force perpendicular to a surface

• Friction (f): Opposes motion along a surface

• Tension (T): Force along a string, rope, or cable

• Applied force (F): Any push or pull applied to the object

What is terminal velocity?

the constant speed an object reaches when the drag force balances the accelerating force (no further acceleration).

what is the normal reaction force

between two surfaces that are touching each other, it acts perpendicular to the two surfaces (at 90 degrees)

what is state friction

the force that stops one surface beginning to move against another surface. The coefficient of static friction is a measure of the amount of friction involved:

what is dynamic friction

the force that resists movement of an object that is already moving which is needed to keep the object moving at a constant velocity.

what method can we use to measure the coefficient of static friction

1. Measure and record the mass of a block with a hook attached to it. Calculate its weight.

2. Place the block on the bench and attach a newton meter.

3. Gently pull the block using the newton meter and record the force when the block just begins to move. 

4. Repeat steps 1-3 five more times and then calculate the mean value. 

5. Calculate μ using the values from steps 1 and 4.  

6. Repeat the method for different surfaces.

Conservation of Momentum law

In a closed system, the total momentum before an event is equal to the total momentum after the event.

whats the relationship between Momentum and Resultant Force

When a resultant force acts on an object, it’s momentum changes.

The rate at which this momentum changes is equal to the resultant force. 

newtons 1st law

An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force

newtons 2nd law

states that the net force acting on an object is directly proportional to its acceleration and directly proportional to the object's mass

newtons 3rd law

states that for every action (force) in nature, there is an equal and opposite reaction.

what is inertia

the natural tendency of an object to resist changes in its state of motion,

what is an accelerometer and what its primary function?

a tiny sensor that measures acceleration. It detects changes in speed and direction and converts that motion into electrical signals.

What are the 3 axes of rotation in 3D space, and what movements do they describe? (linear)

• X: Side to side

• Y: Front to back

• Z: Up and down

How many accelerometers are required to measure motion in three planes (3D)?

Three accelerometers are required, positioned at right angles to one another.

Why are motion equations necessary for devices like smartphones and fitness trackers?

Because accelerometers gather raw data on force/movement, then is calculated using motion equations to determine distance, speed, or specific activities.