Types of Forces a) Contact Forces
- Forces acting between 2 bodies that are in 2 physical contact b) Non-Contact Forces
- Not in physical contact
Weight
- w =mg
Mass
Weight
Measure of inertia of a body
Measure of the gravitational pull on body's mass
Scalar Quantity
Vector Quantity
SI unit: kg
SI unit: Newtons
Same regardless of location
Differs with location
Same regardless of method of measurement
Some methods measured the apparent weight instead of true weight
Center of Gravity
- Point at which the weight of the object appears to act on
Contact Forces a) Normal Contact Force - Acts perpendicularly to the surfaces
- Equals to weight b) Friction Force - Acts opposite to the direction of relative motion c) Tension
- Direction of force always directed away from object
Newton's Laws a) First Law
- states that a body stays at rest or continue to moves with a constant speed in a straight line unless acted upon by a net external force
- also known as Law of Inertia
- the larger the mass, the larger the inertia b) Second law
- states that rate of change of linear momentum of a body is directly proportional to the resultant force acting on it and its direction is in the same direction as this resultant foce
- Linear momentum, p = mv
- Fnet = dp / dt = dmv / dt - Average net force =Δp / Δt
- Impulse, J, is the product of the force and the time interval over which it is applied
- J = FΔ t
- J = Δp
- Area under F - t graph = J = Δp
c) Third Law - If Body A exerts a force on body B, then body B will exert an equal and opposite force on body A
- Conditions to be action-reaction pair:
(i) Equal in Magnitude
(ii) Opposite in direction
(iii) Acting on different bodies
(iv) Same Nature
Principle of Conservation of Linear Momentum
- Total Linear momentum of a system is conserved if no external force acts on the system - Sum of mu = Sum of mv
Types of Collision a) Head-on vs Glancing
- Head-on does not change direction
- Glancing changes direction b) Elastic vs Inelastic
- Elastic = 100% kinetic energy conserved
- Inelastic = Some kinetic energy lost
- Perfectly Inelastic = 2 objects stick together, sharing the same velocity
Relative Speed of Approach/ Separation during Elastic collision
- U1 - U2 = V2 - V1
a) Contact Forces
- Forces acting between 2 bodies that are in 2 physical contact
b) Non-Contact Forces
- Not in physical contact
Weight
- w =mg
Center of Gravity
- Point at which the weight of the object appears to act on
Contact Forces
a) Normal Contact Force
- Acts perpendicularly to the surfaces
- Equals to weight
b) Friction Force
- Acts opposite to the direction of relative motion
c) Tension
- Direction of force always directed away from object
Newton's Laws
a) First Law
- states that a body stays at rest or continue to moves with a constant speed in a straight line unless acted upon by a net external force
- also known as Law of Inertia
- the larger the mass, the larger the inertia
b) Second law
- states that rate of change of linear momentum of a body is directly proportional to the resultant force acting on it and its direction is in the same direction as this resultant foce
- Linear momentum, p = mv
- Fnet = dp / dt = dmv / dt
- Average net force =Δp / Δt
- Impulse, J, is the product of the force and the time interval over which it is applied
- J = FΔ t
- J = Δp
- Area under F - t graph = J = Δp
c) Third Law
- If Body A exerts a force on body B, then body B will exert an equal and opposite force on body A
- Conditions to be action-reaction pair:
(i) Equal in Magnitude
(ii) Opposite in direction
(iii) Acting on different bodies
(iv) Same Nature
Principle of Conservation of Linear Momentum
- Total Linear momentum of a system is conserved if no external force acts on the system
- Sum of mu = Sum of mv
Types of Collision
a) Head-on vs Glancing
- Head-on does not change direction
- Glancing changes direction
b) Elastic vs Inelastic
- Elastic = 100% kinetic energy conserved
- Inelastic = Some kinetic energy lost
- Perfectly Inelastic = 2 objects stick together, sharing the same velocity
Relative Speed of Approach/ Separation during Elastic collision
- U1 - U2 = V2 - V1