Mechanics

Question 0

Ff=uR

Answer 0

• when object is moving or at the point of sliding

- when object not moving F<uR (in equilibrium)

Question 1

Limiting equilibrium

Answer 1

• at the point of sliding
• maximum value of frictional force the surface can exert on object
• friction build up n up till it reach its maximum
• after that the object can move

Question 2

F-Ff=ma

Answer 2

For cars,
P-R=ma
F/v-R=ma

Question 3

a=0

Answer 3

F-Ff=0
F=Ff
P=R
F/v=R

Question 4

a=+ve

Answer 4

Engine power>Resistance, so that vehicle accelerate is positive direction -->
F-Ff=+ve 
F>Ff
P>R
F/v>R

Question 5

a=-ve

Answer 5

Engine power<Resistance, so that vehicle accelerates in negative direction <--
F-Ff=-ve
F<Ff
P<R
Fv<R

Question 6

Constant velocity
Maximum velocity
Minimum velocity

Answer 6

a=0
F-Ff=0
P-R=0
*F/Vmin=R, haven't start accelerating
*F/Vmax=R, doesn't accelerates further

Question 7

a=0

Answer 7

Constant velocity 
Maximum velocity (doesn't accelerate further)
Minimum velocity (haven't start accelerating)
F-Ff=0
P-R=0
*F/Vmin=R
*F/Vmax=R