General physics Flashcards
What are rulers used for?
To measure small distances
What unit are rulers able to measure to?
mm
What is the accuracy of a ruler?
0.1 cm
What is a micrometer screw gauge used for?
To measure very small distances that a ruler cannot
What unit is a micrometer screw gauge able to measure to?
mm
What is the accuracy of a micrometer screw gauge?
0.01 mm
What are vernier calipers used for?
To measure very small distances that a ruler cannot
What unit are vernier calipers able to measure to?
mm
What is the accuracy of a vernier caliper?
0.02 mm
When measuring very small distances which apparatus is most appropriate?
Micrometer screw gauge
What is used to measure large distances?
Tape measure
What unit is a tape measure able to measure to?
m
What is used to measure very large distances?
Trundle wheel
What unit is a trundle wheel able to measure to?
m
What is used to measure volume?
Measuring cylinder
What 2 things does measure cylinder measure?
- Volume of a liquid
2. Volume of an irregular-shaped object
What are used to measure intervals of time
Stop-clocks and stopwatches
How do you measure things that would be difficult to get accurate readings?
- Measure multiples
2. Average
Define speed
Change in distance per unit time
What is the formula for speed?
Distance ÷ time taken
Define velocity
Displacement per unit time
What is the formula for velocity?
Displacement ÷ time taken
Define acceleration
Change in velocity per unit time
What is the formula for acceleration?
Change in velocity ÷ time taken
What does the gradient of a distance-time graph represent?
Speed
What does the gradient of a speed-time graph represent?
Acceleration
What does the area underneath a speed-time graph with constant acceleration represent?
Distance
What is deceleration?
Negative acceleration
What is the acceleration of free fall for a body near to the Earth?
Constant at 10 m/s
What is mass?
The amount of matter contained in an object
What is weight?
A gravitational force
What is the unit of mass?
kg
What is the unit of weight
N
What does mass resist?
Change in motion or change in direction
What is the resistance to change in motion or change in direction by mass called?
Inertia
What is the effect of a gravitational field on a mass?
Weight
Exam tip ; )
- In the absence of air resistance, all objects fall with the same acceleration, regardless of their mass
- So long as air resistance remains insignificant, the speed of a falling object will increase at a steady rate, getting larger the longer it falls for.
Describe terminal velocity
- There is a downwards unbalanced force and the skydiver accelerates
- As the skydiver speeds up, the air resistance increases
- Eventually the air resistance balances the weight and so the skydiver travels at a constant speed
- When the parachute is opened the increase air resistance on the parachute creates an upwards unbalanced force, making the parachuting the slow down
What term is used when air resistance and weight cause a body to move at constant speed?
Terminal velocity
How can weight (and hence mass) be compared?
Using a balance
What is the formula for density?
ρ = mass ÷ volume
Which object will float based on density?
The less dense object will float on a more dense object
What are 3 effects of forces?
- Change in size
- Change in motion
- Change in direction
What is Hooke’s Law?
The extension of a spring is proportional to the applied force
What is the formula for Hooke’s Law?
F = kx
*where k is the spring constant
What is the limit of proportionality?
Point at which load and extension are no longer proportional
What is the elastic limit?
Point at which the spring will no longer return to its original position after being stretched
What is the formula for force?
F = ma
Exam tip ; )
A relationship is said to be proportional if the graph is a straight line going through the origin.
If a graph is a straight line but does not go through the origin the relationship is said to be linear.
Describe circular motion
An object at steady speed in circular orbit is always accelerating as it’s changing direction but gets no closer to the center
What quantity stays constant for circular motion?
Speed