Topic 2 — Motion And Forces Flashcards
(46 cards)
2.1) What is a scalar quantity?
A scalar quantity is a quantity which only has a magnitude (size) but no specific direction
2.2) What is a vector quantity?
A vector quantity is a quantity which has both a magnitude (size) and a specific direction.
2.4) Give some examples of scalar (8) and vector quantities (6).
Scalar Quantities
• Distance
• Speed
• Mass
• Energy
• Volume
• Density
• Temperature
• Power
Vector Quantities • Displacement • Velocity • Weight • Force • Acceleration • Momentum
2.3) What is the difference between velocity and speed?
Velocity is speed in a stated direction and is a vector quantity while speed is a scalar quantity.
2.5) What is velocity?
Velocity is speed in a stated direction
- 6) What is the equation for:
i) average speed
ii) distance travelled
i) average speed (m/s) = distance (m) ÷ time (s)
ii) Distance (m)= speed (m/s) x time (s)
2.7) What does a distance time graph show?
A distance-time graph shows how the distance of an object moving in a straight line (from its starting position) varies over time.
2.7) How is constant speed represented on a distance-time graph?
Constant speed is represented using a straight line.
2.7) Fill in the sentences:
The slope of the straight line on a distance-time graph represents the __________________ of the speed:
- A very __________ slope means the object is moving at a large speed
- A very __________ slope means the object is moving at a small speed
- A flat, _____________ line means the object is stationary (not moving)
1) magnitude
2) steep
3) shallow
4) horizontal
2.7) How can an object moving at a changing speed be represented on a distance time graph?
It can be represented using a curve.
2.7) On a distance-time graph for an object moving at a changing speed:
• A slope that is increasing means the object is __________________
• A slope that is decreasing means the object is __________________
1) accelerating
2) decelerating
2.7) How can the speed of an object be calculated on a distance-time graph?
It can be calculated from the gradient of the line on the distance-time graph:
Speed= gradient= rise ÷ run
2.8) What is acceleration?
Acceleration is a vector quantity that is defined as the rate of change of velocity.
(In other words, how much an objects velocity changes every second)
2.8) What is the equation to calculate the acceleration of an object?
a = v-u ÷ t
a = acceleration (m/s^2)
v = final velocity (m/s)
u = initial velocity (m/s)
t = time(s)
2.8) An object that speeds up is ________________, and therefore has a positive acceleration
An object that slows down is ________________, and therefore has a negative acceleration.
1) accelerating
2) decelerating
2.9) How do you calculate an object that is moving with uniform (constant) acceleration?
v² — u² = 2ax
x = distance (m) v = final velocity (m/s) u = initial velocity (m/s) a = acceleration (m/s²)
2.10) What does a velocity-time graph show?
A velocity-time graph shows how the velocity of a moving object varies with time.
2.10) How can constant acceleration be represented on a velocity-time graph ?
Constant acceleration can be represented as a straight line
2.10) Fill in the sentences:
The slope of the line on a velocity-time graph represents the ____________ of acceleration:
> A ___________ slope means a large acceleration (or deceleration) i.e the objects speed changes very quickly
> A ___________ slope means a small acceleration (or deceleration) i.e the objects speed changes very gradually
> A flat _____________ line means the acceleration is zero i.e the object is moving with a constant velocity
1) magnitude
2) steep
3) gentle
4) horizontal
2.10) How can the acceleration of an object be calculated using a velocity-time graph?
Acceleration of an object can be calculated from the gradient on the velocity-time graph:
acceleration = gradient = rise ÷ run
2.10) What does the area under a velocity-time graph represent?
The area under a velocity-time graph represents the total distance travelled (or displacement) by an object.
2.11) What is speed?
Speed is the distance travelled by an object every second.
- 11) The simplest way to measure speed of an object is to time how long it takes to travel a known distance and use the average speed equation. To do this, you have to use the right sort of equipment to measure the distance and the time.
i) What type of equipment would you use to measure the distance?
ii) What type of equipment would you use to measure the time?
i) Trundle wheel - for long distances
Metre ruler
Measuring tape
ii) A stopwatch
Light gates
2.11) What are light gates and how can light gates be used to measure time?
Light gates are pieces of digital equipment that allow times to be measured more accurately.
• A flag on the top of the moving object blocks a beam of light as it passes through the light gate, triggering a timer to start
• A second light gate (at some fixed distance away) can be used to stop the timer as the object passes through it.