Forces And Motion Equations (unit 1)

Question 0

Acceleration = ?

Answer 0

Acceleration = change in velocity / time

a = (v-u) / t

a = acceleration (m/s/s or m/s^2) 
v = final velocity (m/s)
u = initial velocity (m/s)
t = time (s)

Question 1

Speed = ?

Answer 1

Speed = distance / time

s = d / t

s = speed (m/s)
d = distance (m)
t = time (s)

Question 2

Weight = ?

Answer 2

Weight = mass * gravity

w = m * g

w = weight (N) 
m = mass (kg)
g = gravitational field strength (N/kg or m/s)

Question 3

Density = ?

Answer 3

Density = mass / volume

d = m / v

d = density (kg/m^3 or g/cm^3) 
m = mass (kg or g)
v = volume (m^3 or cm^3)

Question 4

Force = ?

Answer 4

Force = mass * acceleration

F = m * a

F = force (N)
m = mass (kg or g)
a = acceleration (m/s/s)

Question 5

Hooke’s law = ?

Answer 5

F = kx

F = force (N)
x = extension (m)
k = the spring constant (N/m)

Question 6

Moment = ?

Answer 6

Moment = force * perpendicular distance

Moment (N/m)

Question 7

Principle of moments = ?

Answer 7

Sum of clockwise moments = sum of anticlockwise moments

Question 8

Work done = ?

Answer 8

Work done = force * distance

wd = F * d

wd = work done (joules (J))

Question 9

Kinetic energy = ?

Answer 9

Ek = half mv^2

Ek = kinetic energy (J)
m = mass (kg)
v = velocity (m/s)

Question 10

GPE = ?

Answer 10

GPE = mass * delta height * gravity

GPE = m * h * g

GPE = potential energy (J)
m = mass (kg)
h = height (m)
g = gravity (m/s)

Question 11

Relationship between Ek and GPE?

Answer 11

Ek = GPE

Question 12

Power = ?

Answer 12

Power = work done / time taken

P = wd / t

P = power (watts (W))
wd = work done (J)
t = time taken (s)

Question 13

Efficiency = ?

Answer 13

Efficiency = useful output energy / total input energy

x100 to get the percentage

Question 14

Pressure = ?

Solid

Answer 14

Pressure = force / area

P = F / A

P = pressure (Pa)
F = force (N)
A = area (m^2)

Question 15

Pressure = ?

Liquid

Answer 15

Pressure = height * density * gravity

P = h * ro * g

ro = density (kg/m^3)