Can anyone explain the first part of the last question to me pleas, the projectile one, it seems impossible!
Okay to work out T, think about where it will be at it's halfway point, use suvat and consider the vertical bits:
v = 0 ms^-1 as objects are instantaneously at rest at highest point
u = 40 x sin a ms^-1 , vertical component of initial velocity
a = -g , as gravity acts downwards in opposite direction to the motion
t = ?
Now use v= u+at, remembering that this is just for half the time (T/2):
0 = 40sin a - g x (T/2)
T/2 = 40sin a / g
T = 80sin a / g
For R, just think about the horizontal component of the velocity (using cos a) and use suvat, remembering that there isn't any acceleration in this direction as air resistance is negligible. Sub in T = 80sin a / g for time t and you'll get the answer
1) The pulley is smooth so there is no friction 2) The system is in equilibrium. Right side = Left side 20g + rod = 15g So the force in the rod must be -5g It is a thrust as the force is -ve
Okay to work out T, think about where it will be at it's halfway point, use suvat and consider the vertical bits:
v = 0 ms^-1 as objects are instantaneously at rest at highest point
u = 40 x sin a ms^-1 , vertical component of initial velocity
a = -g , as gravity acts downwards in opposite direction to the motion
t = ?
Now use v= u+at, remembering that this is just for half the time (T/2):
0 = 40sin a - g x (T/2)
T/2 = 40sin a / g
T = 80sin a / g
For R, just think about the horizontal component of the velocity (using cos a) and use suvat, remembering that there isn't any acceleration in this direction as air resistance is negligible. Sub in T = 80sin a / g for time t and you'll get the answer
1) The pulley is smooth so there is no friction 2) The system is in equilibrium. Right side = Left side 20g + rod = 15g So the force in the rod must be -5g It is a thrust as the force is -ve
Thanks really appreciated i dont even get question 5
same so do you think past papers for 5 days would be enough to get at least a C ?
5 days is more than enough! I wish I had that much time! I only started revising yesterday...I'm in A2 and resitting...need an A in mechanics...not had much time to revise though due to synoptic papers for my other subjects!