2 Motion and Force Flashcards
In which part of the graph is the object moving the fastest?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/087/q_image_thumb.png?1509797451)
A
-gradient of the line is the steepest
gradient = rise/run = distance/time = speed
What is the difference between upthrust force and reaction force?
Up thrust is created when an object displaces a fluid, such as a boat displacing water.
Reaction force is the upward force on a block which is resting on a solid surface.
What is the unit for force?
newton or N
What feature of a velocity-time graph gives the acceleration?
acceleration = gradient of velocity-time graph
Masses are attracted to each other. Planets are attracted to each other. Name the force acting between them.
Gravitational force
Describe what is happening in the graph and explain how you know.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/095/q_image_thumb.png?1510239690)
The object is accelerating or speeding up
Gradient is increasing, therefore velocity is increasing.
If an object has a 50 N force acting North and a 50N force acting south, what is the resultant force?
50 N - 50 N = 0 N
What is the unit for displacement or distance travelled?
metre or m
F= ma
rearrange the equation to give a
a = F/m
Which of the following quantities are vectors?
mass
acceleration
force
speed
velocity
time
acceleration
force
velocity
In which part of the graph is the object travelling back to the start.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/101/q_image_thumb.png?1509797544)
C
-gradient of the line is negative
velocity is negative
-travelling in opposite direction to part A
What is the equation for average speed?
average speed = total distance travelled/ time taken
What type of force acts forward on a rocket?
Thrust
the rocket throws gases out backwards to create thrust forward
What type of force is reduced if an object is streamlined?
air resistance
What feature of a velocity-time graph gives the distance travelled?
distance = area under a velocity-time graph
What can forces do to an object?
- change the speed (accelerate or decelerate)
- change the shape
- change the direction
A horizontal line on a velocity-time graph shows?
constant velocity, no acceleration
If a book is at rest on a table, what two forces are acting on it?
downward gravitational pull (or weight)
upward reaction force from table
What feature of a distance-time graph gives the speed?
speed = gradient of distance-time graph
Which ticker tape shows an object which is decelerating?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/117/q_image_thumb.png?1510778083)
ticker tape Z
- dots get closer together
- object is covering less distance per unit time
- object is slowing down
Friction forces always oppose motion.
What can be done to reduce friction when an object is sliding on a surface?
- use oil or grease on the surfaces
- make the surfaces smoother
- blow air between the surfaces
In which part of the graph is the object stopped?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/119/q_image_thumb.png?1509797352)
B
Gradient is zero therefore speed is zero