The Student Room Group
Reply 1
To find the upward acceleration you just need to use the mass of the parcel and the tension in the string. I'm assuming that acceleration due to gravity exists here by the way. Assume that the lift is accelerating upwards with acceleration aa; then the equation of motion (F=ma) for the parcel is T=mgmaT = mg - ma (draw a diagram with arrows to see why the ma term is negative); then you can solve for a (since you know T, m and g).

For (b) notice that the total mass of the man and the parcel is 80kg, so that is effectively his 'weight' (assuming the parcel isn't touching the floor). Again you can use the equation R=mgmaR = mg - ma, where this time R is the normal reaction and m is the weight of the man and the parcel combined.
Reply 2
Thank you very much :smile:

Latest