M1 Questions

Q.1 A particle is moving along a straight line with constant acceleration. In an interval of T seconds it moves D metres; in the next interval of 3T seconds it moves 9D metres. How far does it move in a further interval of T seconds?

...i made a rough velocity-time graph but i dont have the velocities so all i get is loads of equations and then i just get confused what to substitute and where!!!

Q.2 A load of weight 7kN is being raised from rest with constant acceleration by a cable. After the load has been raised 20 metres, the cable suddenly becomes slack. The load continues upwards for a distance of 4 metres before coming to instantaneous rest. Assuming no air resistance, find the tension in the cable before it became slack.

I get the equation .... T - 7000 = 700a
but im not sure what happens after the cable became slack.

Reply 1

latentcorpse

12

for it not to be slack tension = weight = 7kN

Reply 2

latentcorpse

12

no thats rubbiosh ignore me

Reply 3

suneilr

3

For q1) v= d/t = 9D/3T =3D/T

u=d/t = D/T

a=(v-u)/t
v-u= 2D/T

a= 2D/T/T = 2D/T^2

s=ut+0.5at^2
=D/T * T + 0.5 * 2D/T^2 * T^2
= 2D + D
=3D

Reply 4

e-n-i-g-m-a

OP

The answer in the book is 5D metres ... how can the velocity be 9D/ 3T when the particle is traveeling with constant acceleration and not constant velocty

Reply 5

e-n-i-g-m-a

OP

Help !!!

Reply 6

Malik

12

e-n-i-g-m-a

The answer in the book is 5D metres ... how can the velocity be 9D/ 3T when the particle is traveeling with constant acceleration and not constant velocty

speed= distance/time thus giving u=D/T and v=9D/t which allows you to find acceleration, which you can then use to find distance.

Reply 7

e-n-i-g-m-a

OP

i still dont think we can use velocity = distance / time ..shouldnt we use the equations of motion since the object is moving with constant acceleration ...i plotted a graph ..and we get a startight line so the velocity is not constant.

Reply 8

Malik

12

e-n-i-g-m-a

i still dont think we can use velocity = distance / time ..shouldnt we use the equations of motion since the object is moving with constant acceleration ...i plotted a graph ..and we get a startight line so the velocity is not constant.

.
I think you can, I am not saying the velocity is constant, what I am saying is you CAN use it to find the velocity's(yes plural) at the beginning and the end. And then you can go and you can go use v=u+at to find the constant acceleration.

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