Our Dynamic Universe: Part 1 Flashcards

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1
Q

What are the Equations of Motion?

A

V=u+at

S= ut+1/2at^2

V^2= u^2+2as

S= 1/2 (u+v)t

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2
Q

How do you find the displacement from a V/t graph?

A

Find the area underneath the graph

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3
Q

What does the gradient of a displacement-time graph give?

A

Velocity

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4
Q

What does the gradient of a velocity-time graph give?

A

Acceleration

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5
Q

What does the area of a velocity-time graph give?

A

Displacement

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6
Q

Describe the force, velocity and acceleration of vertical motion?

A

Force: weight

Velocity: changes with time

Acceleration: -9.8ms^-2

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7
Q

Is horizontal velocity, in general, increasing, decreasing or constant?

A

Constant

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8
Q

Describe, in general, the force, velocity and acceleration of horizontal motion?

A

Forces: none

Velocity: Constant

Acceleration: None

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9
Q

What equation is used to find the horizontal component of an object?

A

V(h)= Vcos(angle)

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10
Q

What equation is used to find the vertical component of an object?

A

V(v)= Vsin(angle)

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11
Q

What is Newton’s First Law?

A

“An object will remain at rest or move with constant velocity unless acted on by an unbalanced force”

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12
Q

What is Newton’s Second Law?

A

“An object will accelerate when acted upon by an unbalanced force”

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13
Q

What is the definition of a Newton?

A

The force required to accelerate a mass of 1kg at a rate of 1ms^-2

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14
Q

What does ‘an acceleration of 1ms^-2’ mean?

A

The velocity changes by 1ms each second

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15
Q

Is force a Vector or Scalar quantity?

A

Vector, because it shows magnitude and direction

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16
Q

What equation is used to find the Force of an object?

A

F=ma

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17
Q

What happens if you accelerate upwards and decelerate downwards?

A

You feel as if your weight has INCREASED.

18
Q

What happens if you accelerate downwards and decelerate upwards?

A

You feel as if your weight has DECREASED.

19
Q

What happens during free fall?

A

The person will fall at the same rate as the lift, for example. The reading would therefore be 0N

20
Q

How do you find the unbalanced force on a rocket?

A

F(unbalanced)=Thrust(Weight+Air Resistance)

21
Q

What happens if F(unbalanced)< 0

A

The rocket will not take off

22
Q

As lift off continues…

A
  1. Fuel is used up, mass decreases, weight decreases, F(un) increases
  2. Air resistance decreases as air gets thinner
  3. ‘g’ decreases as further from planet
23
Q

How do you find horizontal force component?

A

F(h)= Fcos(angle)

24
Q

How do you find vertical force component?

A

F(v)= Fsin(angle)

25
Q

To find conservation of energy…

A

Ep= Ek

So

v= 2gh (square root 2gh)

26
Q

What is a collision?

A

When two or more objects come together and move off, directions may change, and objects may stick together

27
Q

What is an explosion?

A

When an object separates into two or more moving parts

28
Q

What is momentum?

A

The product of an objects mass and velocity

29
Q

The equation used to find momentum is….

A

p= mv

p- momentum (kg/ms)
m- mass
v- velocity

30
Q

The Law of Conservation of Momentum is…

A

Total momentum before=Total momentum after

31
Q

In an inelastic collision…

A

Total Energy- Conserved

Kinetic Energy- Not Conserved

Total Momentum- Conserved

32
Q

In an elastic collision…

A

Total Energy- Conserved

Kinetic Energy- Conserved

Total momentum- Conserved

33
Q

In an explosion…

A

Total energy- Conserved

Kinetic Energy- Not Conserved

Total Momentum- Conserved

34
Q

m1u1 +m2u2= m1v1 +m2v2 is used…

A

When objects stick together

35
Q

m1u1+m2u2=(m1+m2)v is used…

A

When objects do not stick together

36
Q

If the collision is elastic…

A

Energy is Conserved

37
Q

If the collision is inelastic…

A

Energy is not Conserved

38
Q

Total momentum before explosion=Total momentum after explosion is given the equation…

A

0= m1v1+m2v2

REMEMBER: total momentum before explosion is 0

39
Q

Equation for Impulse is…

A

Ft= mv-mu

40
Q

Impulse=forcextime=the change in momentum=mv-mu. How do you find impulse from a force-time graph?

A

Find the area under the f/t graph