Edexcel PHYSICS Doubts

[dk bose]

I have got a physics doubt.its 4m Edexcel A2 physics students buk.page no 35,exam zone: topic 1,Question no 5.the question is as follows-
palaeontologists are able to deduce much about the behaviour of dinosaurs from the study of fossilised footprints.The tracks in the attachment show the path of a Tyrannosaurus rex as it attacks a stationary Triceratops.The time between the footprints is 0.62s.(a)Show that the maximum speed of the Tyrannosaurus rex is about 10m/s.(b)the tyrannasaurus rex has a mass of 7000kg.calculate the momentuemjust before it hits the triceratops.(c)Triceratopshas a mass of 5000kg.calculate their combined speed immediately after the collision.(d)The skull of tyrannosaurus rex is heavily reinforced to withstand the force produced in such a collision.Calculate the force exerted on the Tyrannosaurus rex if the time taken to reach their combined speed after the collision is 0.30s.

[astarmathsandphysics]

See attachment

[The Golden Girl =D]

 an Airplane with a wingspan of 30m flies at a speed of 100m/s perpendicular to the earth's magnetic field as shown. the earth's magnetic field at the airplane location 60*10^-6 T

show the direction of induced e.m.f.

Diagram attached having answer. the pink arrow shows the direction of e.m.f.

how did we know the direction of the resistance 

thx

[The Golden Girl =D]

^ I've got a test tomorrow =[ Anyone ?

[iluvme]

I believe its the air resistance which usually opposes the motion of the plane.

[The Golden Girl =D]

but they didn't state the motion of the plane in the question, so u they assumed it moved forward ( as in the to Right) , is that right or am I just  blabbing?

[astarmathsandphysics]

Planes do fly forward. Do you mean the voltage?
Use the left hand rule - it is upwards as you drew it in the diagram.

[The Golden Girl =D]

I meant it's direction of Motion. The arrow I drew was the direction of the induced e.m.f which is the opposit of resistance so how did we know the direction of motion of the airplane even though it wasn't stated in the Question , so you simply assumed that it moved forward right? and secondly ,why did the direction of induced e.m.f turn out that way :S (Pink arrow that is in the diagram I drew )

This topic sure does confuse me =[

can u explain in detail (perhaps a diagram could help) thanks sir =]

[astarmathsandphysics]

The direction of the current is upwards sorry. The current is always taken as positive, but the current is actually carried by negatively charged electrons, which move downwards.The electrons will flow towards the positive terminal so the positive termainal is at the bottom and the negative at the top.

[The Golden Girl =D]

Sorry for asking too many Questions but how did you know that Current is Upwards :$

[astarmathsandphysics]

I used fleming's left hand rule
http://astarmathsandphysics.com/a_level_physics_notes/electricity/a_level_physics_notes_flemings_left_hand_rule.html

[The Golden Girl =D]

Thanks Sir =]

[astarmathsandphysics]

no probs

[SZM]

i want to ask u something, that in edexcel physics unit 1, under mechanics, the questions based on the textbuk are not sufficient, so can i do more questions in Mechanic 1  of Mathematics. If i do mechanic 1 questions, is that more than enough or not? do i have to do any other questions???

i know pastpaper questions, questions from revison guide, but i am teling u, apart from that, where can i do more questions based on mechanic in edexcel physics unit 1.

Under edexcel physics unit 1, under mechanic, the chapters are
1. motion equations and graphs
2. Combining and resolving vectors.
3. Force and acceleration
4. Gravity and free-body diagrams
5. Projectile motion
6. Work and power
7. Energy and energy conservation.

under mechanic 1, which is M1, the topics are-
1. Mathematical model in mechanics
2. Kinematics of a particle moving in a straight line
3. Dynamics of a particle moving in a straight line or plane
4. Statics of a particle
5. Moments
6. Vectors

under mechanic 2, which is M2, the topics are-
1. kinematics of a particle moving in a straight line
2.Centres of mass
3.Work, energy and power
4.Collisions
5.Statics of rigid bodies

so tel me wat should i do?? i need ur suggestion to this matter.

waitin for ur reply.
need ur reply urgenlty

[astarmathsandphysics]

If you have run out of questions to do, you may have done enough but you could try papers from different boards eg IB. Doing m1 papers as well sounds good. I shouldn't worry about topics - just do as many papers as you have time for.