M3 Kinematics and Linear Motion

Question 1

define speed

give unit

Answer 1

distance per unit time

ms^-1

Question 2

define velocity

give unit

Answer 2

rate of change of an object’s displacement

ms^-1

Question 3

define acceleration

give unit

Answer 3

rate of change of an object’s velocity

ms^-2

Question 4

define displacement

give unit

Answer 4

distance moved in a stated direction

m

Question 5

define instantaneous speed

Answer 5

speed at any particular moment

Question 6

define average speed

Answer 6

total distance travelled over a given amount of time

Question 7

on a displacement-time graph what does it mean if it is a straight diagonal line?

Answer 7

constant velocity

0 acceleration

Question 8

on a displacement-time graph what does it mean if it is a positive curve

Answer 8

changing velocity

increasing acceleration

Question 9

on a displacement-time graph what does it mean if it is a negative curve

Answer 9

changing velocity

decreasing acceleration

Question 10

what is the gradient on a velocity-time graph

Answer 10

the acceleration

Question 11

on a velocity-time graph what does the area between the graph and the x axis equal

Answer 11

displacement of the object

Question 12

what are the 2 conditions for SUVAT equations

Answer 12

motion in a straight line

an object moving with a constant acceleration

Question 13

what does SUVAT stand for and how would you use it in a question

Answer 13

s= displacement
u= initial velocity
v= final velocity
a= acceleration
t= time

you fill in all the parts you know from the question and pick one of the four SUVAT equations and work out the asked thing

Question 14

A stone is thrown off the top of a 24m high cliff. It’s initial velocity is 15ms-1 in the horizontal direction.

1) How long does it take to fall into the sea?
2) What is its range?
3) Find the magnitude and direction of its velocity as it hits the water.

Answer 14

Horizontal / verticle:
u = 15 / 0
v = 15 / ?
a = 0 / 9.81
t = ? / ?
s = ? / 24

1) s= ut + 1/2 at^2
24 = 5t^2
t= 2.2 s

2) s = 0.5(u+v)t
= 1.1 X 30
= 33 m

3) v = u + at
= 9.81 X 2.2
= 21.7 ms^-1
use pythag
angle = tan^-1(21.7/15)
= 55 degrees

Question 15

how do you deal with a projectile at an angle

Answer 15

resolve the velocity vector into its horizontal and verticle components

Uh = Ucosx
Uv = Usinx

Question 16

in a projectile question what do you SUVAT will be in the horizontal and verticle direction if something is being thrown upwards to the highest point

Answer 16

Horizontal / Verticle
S = range / height (m)
U = ucosx / usinx (ms^-1)
V = ucosx / 0 (ms^-1)
A = 0 / -9.81 (ms^-2)
T = t / t (s)

Question 17

define density

give units

Answer 17

mass per unit volume

kgm^-3

Question 18

A gold block has a density of 19 320 kg m^-3. What is the volume of a 275 g gold block in cm^3?

Answer 18

volume= 0.275/19320=1.42×10^(−5) m^3=14.2 cm^3

Question 19

Define pressure

Answer 19

force per unit area

Question 20

What is fluid pressure

Answer 20

An object submerged in a fluid has a pressure that depends on the density of the fluid and the depth of the object.

The denser the fluid, the more particles there are to collide with the object.

The deeper the object, the greater the weight of the particles above the object and so pressure increases with depth.

Question 21

When does upthrust occur?

Answer 21

when objects are submerged in fluids because the top and bottom of these objects are at different depths and so experience different forces.

Question 22

what is the equation for upthrust?

Answer 22

upthrust = (h2−h1)ρgA

Question 23

what is Archimedes principle

Answer 23

When a body is completely or partially immersed in a fluid, it experiences an upthrust equal to the weight of the fluid that it has displaced.

Question 24

define free fall

Answer 24

only gravity is acting on an object

the only force acting on an object is weight

Question 25

in free fall is gravity positive or negative

Answer 25

negative