All Mechanics DOUBTS HERE!!!

[Malak]

Anyone?

The most I need is the free body diagram 'cause that is where I think I am messing up

The answer for both parts is 9.8N

[astarmathsandphysics]

Cant find any mistake in my working but doesnt seem right. Let me know.

[WARRIOR]

M2 (edexcel book )

EXERCISE 1 A , Q 14 . I got a) but i dont know how to get b

[astarmathsandphysics]

Don't have the book.
Post the question.

[LekhB]

A particle,P,of mass 0.3kg,is moving in a straight line on a rough horizontal floor.The speed of P decreases from 7.5m s-1 to 4 m s-1 in time T seconds.Given that the coefficient of friction between P and the floor is 1/7(one divided by 7) find:
(a) the magnitude of the frictional force opposing the motion of P.
(b) The value of T.

[astarmathsandphysics]

see attachment

[LekhB]

Thank you!

I had some problems with this one too.

A box of mass 4.5 kg is pulled at a constant speed of 2 m/s alone a rough horizontal floor by a horizontal force of magnitude 15 N.
(i) Find the coefficient of friction between the box and the floor.


The horizontal pulling force is now removed. find
(ii) the deceleration of the bx in the subsequent motion
(iii) the distance travelled by the box rom the instant the horizontal force is removed until the box comes to rest.

And this one too:






A particle of mass 0.5 kg is placed on a rough plane inclined at an angle ? to the horizontal where sin ?= 4/5. Initially, the particle is at rest under the action of a force P N applied in a upward direction parallel to the plan. Given that the coefficient of friction between the particle and the plan is 2/5, calculate the value of P when

(i) the particle is about to move up the plane,
(ii) the particle is about to move down the plan.

If the force P is now removed, calculate the acceleration of the particle down the plane.

[sweetsh]

Thank you!

I had some problems with this one too.

A box of mass 4.5 kg is pulled at a constant speed of 2 m/s alone a rough horizontal floor by a horizontal force of magnitude 15 N.
(i) Find the coefficient of friction between the box and the floor.


The horizontal pulling force is now removed. find
(ii) the deceleration of the bx in the subsequent motion
(iii) the distance travelled by the box rom the instant the horizontal force is removed until the box comes to rest.

And this one too:






A particle of mass 0.5 kg is placed on a rough plane inclined at an angle ? to the horizontal where sin ?= 4/5. Initially, the particle is at rest under the action of a force P N applied in a upward direction parallel to the plan. Given that the coefficient of friction between the particle and the plan is 2/5, calculate the value of P when

(i) the particle is about to move up the plane,
(ii) the particle is about to move down the plan.

If the force P is now removed, calculate the acceleration of the particle down the plane.

Hello,
I apologize I won't be able to answer your question i'm on my mobile now but a very good hint is in every question like that, draw the plane inclined with the particular object as a "block" or a "circle" and then put arrows for each force acting on it(i.e gravity, friction, N, .... )

[astarmathsandphysics]

Yes draw a diagram. See attachment.

[WARRIOR]

A particle P moves along the x-axis . At t seconds (where t =>0 ) the velocity of P is
[3t(sq) -12t + 5 ] m/s
When t=0 , P is at ORIGIN O. Find

a) The velocity of p when its acceleration is zero
b)the values of t when p is again at O
c) The distance travelled by p in the interval 3=<t=<4

i got a and b but i dont get c at all.
I understand by getting the maximu displacement , when V = 0 , i get 13.12... . And at t = 3 displacement is -12 , and at t= 4 displacement is -12 again !  So displacement must be
 (13.12-12)X2 ?? explain please the right answer is 48

[astarmathsandphysics]

Am looking at this now

[astarmathsandphysics]

I got 1.926 and I cant post my working until my scanner recovers from the thumping I gave it

[WARRIOR]

I got 1.926 and I cant post my working until my scanner recovers from the thumping I gave it

This is from the M2 Edexcel book . Page  18  ,Exercise 1B question 10 ! 

The answer at the back
a)7
b)1,5
c)48m

Thanks anyway !

[astarmathsandphysics]

I didn't get a  b or c
Check you have the correct page

[WARRIOR]

At time t seconds , the force F newtons acting on particle P, of mass 0.5 KG , is given by
F= ( 3t ) i  + (4t-5)j .

When t=1 , the velocity of P is 12 i m/s
Find velocity of P after t seconds
The angle the direction of motion of p makes with i when t=5 .


also i woudl like to know , when the question says for example
Find t when v is paraller to i . This means j = 0
but when he says i+j or i-j , what does this mean?
 Gradient = 1 and gradient = -1