Our Dynamic Universe: Part 1 Flashcards
What are the Equations of Motion?
V=u+at
S= ut+1/2at^2
V^2= u^2+2as
S= 1/2 (u+v)t
How do you find the displacement from a V/t graph?
Find the area underneath the graph
What does the gradient of a displacement-time graph give?
Velocity
What does the gradient of a velocity-time graph give?
Acceleration
What does the area of a velocity-time graph give?
Displacement
Describe the force, velocity and acceleration of vertical motion?
Force: weight
Velocity: changes with time
Acceleration: -9.8ms^-2
Is horizontal velocity, in general, increasing, decreasing or constant?
Constant
Describe, in general, the force, velocity and acceleration of horizontal motion?
Forces: none
Velocity: Constant
Acceleration: None
What equation is used to find the horizontal component of an object?
V(h)= Vcos(angle)
What equation is used to find the vertical component of an object?
V(v)= Vsin(angle)
What is Newton’s First Law?
“An object will remain at rest or move with constant velocity unless acted on by an unbalanced force”
What is Newton’s Second Law?
“An object will accelerate when acted upon by an unbalanced force”
What is the definition of a Newton?
The force required to accelerate a mass of 1kg at a rate of 1ms^-2
What does ‘an acceleration of 1ms^-2’ mean?
The velocity changes by 1ms each second
Is force a Vector or Scalar quantity?
Vector, because it shows magnitude and direction
What equation is used to find the Force of an object?
F=ma
What happens if you accelerate upwards and decelerate downwards?
You feel as if your weight has INCREASED.
What happens if you accelerate downwards and decelerate upwards?
You feel as if your weight has DECREASED.
What happens during free fall?
The person will fall at the same rate as the lift, for example. The reading would therefore be 0N
How do you find the unbalanced force on a rocket?
F(unbalanced)=Thrust(Weight+Air Resistance)
What happens if F(unbalanced)< 0
The rocket will not take off
As lift off continues…
- Fuel is used up, mass decreases, weight decreases, F(un) increases
- Air resistance decreases as air gets thinner
- ‘g’ decreases as further from planet
How do you find horizontal force component?
F(h)= Fcos(angle)
How do you find vertical force component?
F(v)= Fsin(angle)
To find conservation of energy…
Ep= Ek
So
v= 2gh (square root 2gh)
What is a collision?
When two or more objects come together and move off, directions may change, and objects may stick together
What is an explosion?
When an object separates into two or more moving parts
What is momentum?
The product of an objects mass and velocity
The equation used to find momentum is….
p= mv
p- momentum (kg/ms)
m- mass
v- velocity
The Law of Conservation of Momentum is…
Total momentum before=Total momentum after
In an inelastic collision…
Total Energy- Conserved
Kinetic Energy- Not Conserved
Total Momentum- Conserved
In an elastic collision…
Total Energy- Conserved
Kinetic Energy- Conserved
Total momentum- Conserved
In an explosion…
Total energy- Conserved
Kinetic Energy- Not Conserved
Total Momentum- Conserved
m1u1 +m2u2= m1v1 +m2v2 is used…
When objects stick together
m1u1+m2u2=(m1+m2)v is used…
When objects do not stick together
If the collision is elastic…
Energy is Conserved
If the collision is inelastic…
Energy is not Conserved
Total momentum before explosion=Total momentum after explosion is given the equation…
0= m1v1+m2v2
REMEMBER: total momentum before explosion is 0
Equation for Impulse is…
Ft= mv-mu
Impulse=forcextime=the change in momentum=mv-mu. How do you find impulse from a force-time graph?
Find the area under the f/t graph
