7. A block of mass 2 kg slides down an inclined plane which makes an angle of 30 with the horizontal. The coefficient of friction between the block and the surface is 3/2.
(i) What force must be applied to the block so that the block moves down the plane without acceleration?Type equation here.
(ii) What force should be applied to the block so that it can move up without any acceleration?
(iii) Calculate the ratio of the powers needed in the above two cases, if the block moves with the same speed in both the cases.

Question

7.	A block of mass 2 kg slides down an inclined plane which makes an angle of 30  with the horizontal.  The coefficient of friction between the block and the surface is  3/2.
(i)	What force must be applied to the block so that the block moves down the plane without acceleration?Type equation here.
(ii)	What force should be applied to the block so that it can move up without any acceleration?
(iii)	Calculate the ratio of the powers needed in the above two cases, if the block moves with the same speed in both the cases.

anonymous · Answer

(i)$$-W*\sin(30)$$

aravindg · Answer

attachment

aravindg · Answer

13.	Three blocks A,B and C 
Weighing 1,8 and 27 kg respectively
Are connected as shown in the figure
With an inextensible string and are
Moving on a smooth surface.  T3
Is equal to 36 Newton.  Find T2?

phi · Answer

Treat the 3 blocks as 1 system with mass= 36 kg
F= ma, or 36=36a, and a= 1m/s^2
Each individual block is accelerating at this rate.
So T2 must be the force required to accelerate a mass of (1+8) at 1 m/s^2
T2= 9 N