Equations of Motion Definitions

Question 1

Difference between a scalar and a vector

Answer 1

Vector has both magnitude and direction, whereas scalar only has magnitude.

Question 2

Scalar Examples

Answer 2

speed, mass, time, energy, power

Question 3

Vector Examples

Answer 3

displacement, velocity, acceleration, force, weight

Question 4

Displacement

Answer 4

distance in a given direction

Question 5

Velocity

Answer 5

rate of change of displacement (change in displacement/time taken)

Question 6

Acceleration (ms^-2)

Answer 6

rate of change of velocity (change in velocity/time taken)

Question 7

Uniform Acceleration

Answer 7

Where the acceleration is constant.

Question 8

Accelerates

Answer 8

velocity increases with time

Question 9

Decelerates

Answer 9

velocity decreases with time

Question 10

Average Acceleration

Answer 10

(final velocity-initial velocity)/time taken

Question 11

Displacement-time Graph GRADIENT

Answer 11

velocity

Question 12

Velocity-Time Graph AREA

Answer 12

displacement

Question 13

Velocity-Time Graph
GRADIENT

Answer 13

acceleration

Question 14

Acceleration-Time Graph AREA

Answer 14

change in velocity

Question 15

Average Velocity Equation

Answer 15

total displacement / total time
(can be 0 if object returns to starting point after total time)

Question 16

Instantaneous Velocity at a Point

Answer 16

rate of change of displacement at that point - gradient at a point on a displacement time graph

Question 17

Where to use SUVAT equations of motion?

Answer 17

only apply in situations where acceleration is uniform

v = u + at
s/t = (v+u)/2
s = ut + 0.5at^2
v^2 = u^2 +2as

Question 18

Free Fall

Answer 18

situation where gravitational force is the only force acting on an object

Question 19

Drag

Answer 19

Resistive force (air resistance) that acts to oppose motion (for objects moving slowly in air, drag force is negligible)

Question 20

Terminal Velocity

Answer 20

Maximum speed of a falling object reached when the forces of weight and drag are equal

Question 21

Conditions for an object falling at terminal velocity

Answer 21

resultant force on object is 0 (weight and drag are balanced)
acceleration is zero (F=ma)
object travels at constant velocity

Question 22

Factors affecting drag force on an object

Answer 22

shape of object
its speed
the viscosity of the fluid/gas - measure of how easily fluid flows past a surface

Question 23

Explain why an object reaches terminal velocity when falling through air

Answer 23

object dropped from rest so only force acting is weight
resultant force on object producing acceleration (2nd Law)
as velocity increases, drag increases
resultant force decreases
object accelerates but at a decreasing rate
eventually drag force = weight
forces are balanced - no resultant force - no acceleration
object falls at uniform velocity (terminal)

Question 24

Horizontal and Vertical Motion of a Projectile

Answer 24

both horizontal and vertical motion are independent

gravity only acts vertically - projectiles only experience acceleration due to gravity in vertical direction

Question 25

Horizontal/Vertical Motion of a Projectile in Absence of Resistive Forces

Answer 25

Horizontal Motion : no force horizontally, no acceleration therefore uniform (constant) velocity.

Vertical Motion : constant force due to weight, uniform (constant) acceleration down due to G

Question 26

Instantaneous Velocity

Answer 26

The velocity of an object at a specified point in time. Can be found from displacement-time graph by drawing a tangent and calculating gradient.

Question 27

Average Velocity

Answer 27

The velocity of an object over a specified time frame. Can be found by dividing final displacement from time taken.