2 Mechanics Flashcards
The value and unit for downwards acceleration due to gravity is … ?
9.81 m s − 2.
How can you read the instantanous velocity from a displacement-time graph?
The instantaneous velocity of an object is equal to the gradient of the displacement–time graph at that instant.
Which of the lines shows a decelerating object and why?
D At time 0 the gradient is steeper, which means the objects is approaching faster towards position 0 (x-axis) than later.
What does the area under a graph always represent?
Example: Y- axis shows distance X- axis shows speed
The area under the graph represents x times y
Time in s times Speed in ms^-1 Results in distance in m
What is a drag force?
Drag is opposing motion through a fluid
sometimes called fluid resistance.
When a rocket burned all its fuel, this is the moment, where
A The vertical displacement reaches its maximum
B The acceleration turns negative
C The velocity turns negative
B
without fuel the gravitational pull creates a negative acceleration.
The rockets velocity will start to reduce but is not instantly negative.
A car can travel 100 m from rest in 8.2 s.
What is the average acceleration?
3.0 ms-2
Why do skydivers reach their maximum speed before they open the parachute and although the gravitational pull still acts on them.
The air (fluid) resistance is opposing motion.
The drag force equalizes the gravitational force.
When a cannonball is shot (in a simple harmonic motion) the horizontal velocity in its highest point is…
A. Starting to decrease
B. Starting to increase
C. Not affected
C
the gravitational pull is only affecting the velocity in vertical direction.
Define displacement
Displacement is defined as the distance in a given direction from a fixed reference point.
How can you read from an acceleration- time graph, whether the velocity of an object is constant or not.
The line will be curved.
The same applies for a displacement-time graph.
What does the green area under a velocity-time graph represent?
Displacement The area under a graph always repesents the unit Y divided the unit X. velocity (ms-1) divided by time (s) cancels out the s and it remains displacement with the unit (m).
Define acceleration.
What is the suvat formular for acceleration (a) ?
Acceleration, a, is defined as the rate of change of velocity with time
From which part of the graph can you tell, if the object moving up and down has a propulsion system or not.
The change rate of velocity increases over the first 3 seconds, it must have a propulsion system. If the object were only shot, the curve would be bent to the other direction.
Force is mass times ……
What is the SI - unit for force?
What is the fundamental SI unit ?
Acceleration
Newton
kgms-2
The graphs shows speed over time.
Where is the acceleration of the object greatest.
B
because that is where the gradient is steepest and positive.
In which sections of the graph is the acceleration zero.
B and E
Draw the acceleration graph.
