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A Level Physics > Dynamics > Flashcards

Flashcards in Dynamics Deck (13):
1

N1L

States that an object at rest will remain at rest and an object in motion will remain in motion at constant velocity in a straight line in the abscence of external resultant force

2

Inertia

Reluctance of a body to change its state of rest or uniform motion in a straight line

3

Mass

Measure of a body's resistance to change in velocity

4

Weight

Force acting on a mass due to gravitational field

5

Why do ppl feel weightless

No contact force, eg astronaut traveling in space

6

Linear momentum

Linear momentum of a body is the product of the mass and its velocity. The linear momentum is in the same direction as its velocity
p=mv

7

N2L

States that the rate of change of momentum of a body is directly proportional to the resultant force and occurs in the direction of the resultant force
(delta p/delta t)=F

8

N3L

States that if body A exerts a force on body B, then body B exerts a force of the same type that is equal in magnitude and opposite in direction on body A

9

Impulse

Defined as the product of a force F acting on an object and the time delta t for which the force acts
Impulse=F(delta t)
Also area under F-t graph

10

Principle of Conservation of Linear Momentum

States that the total momentum of a system remains constant provide no external resultant force acts on the system

11

Difference between Elastic, Inelastic & Perfectly inelastic collisions

Elastic: Total momentum conserved, KE constant
Inelastic: Total momentum conserved, KE not constant
Perfectly inelastic: Total momentum conserved, KE not constant (stick tgt)
Difference in KE is due to dissipative forces

12

Useful formulas

m1u1+m2u2=m1v1+m2v2
u1-u2=v2-v1 (only for elastic collision)

13

Special cases for 1D elastic collisions

1. m1=m2
u1=u, u2=0 -> v1=0,v2=u
Simply exchange velocities
2. m1 << m2
u1=u, u2=0 -> v1=-u,v2=0
Reversed
3. m1>>m2
u1=u,u2=0 -> v1=u,v2=2u