Question

Anders weighs 70.5 kg. He is carrying a bag with the mass of 7.5 kg och is going down in an elevator that is moving with a constant speed.

a) How big is the force from the elevator floor to Anders?
Suddenly the elevator starts to fall free
b) how big is the force on Anders now?
c) what happens to the bag if he drops it?

How to approach b) and c)?

Answer 1

Total mass m=70.5+7.5=78kg
Right?

Answer 2

Tell me weight w=?

Answer 3

775N?

Answer 4

@shamim

Answer 5

I wrote wrong in my question, he have the mass of 70 kg

Answer 6

If velocity is constant. Acceleration a=0
Right?

Answer 7

So totsl mass m=?

Answer 8

yes

Answer 9

U know weight w=mg

Answer 10

But I know a), it is the same as his force but opposite direction! so its 775N

Answer 11

Both weight n force has same unit newton. Right?

Answer 12

So force n weight is equivalent

Answer 13

775?

Answer 14

Andrew will apply a force on the floor of lift is its weight w

Answer 15

Yes

Answer 16

Ya lift will apply equal n opposit force on andrew

Answer 17

yes, thats what makes him dont go through the elevator floor

Answer 18

Make clearer plz. Mass m=?

Answer 19

m=70+7.5

Answer 20

Going to bathroom. Coming soon. Sorry

Answer 21

70 kg + 7.5 kg = 77.5

Answer 22

So w=mg=77.5*9.8=?

Answer 23

Or u can use g=10m/s

Answer 24

YES!!!! 775 N I have already said that? two times

Answer 25

R u there?

Answer 26

yes

Answer 27

Shamim, I need help with question b and c, can you just write it in one message? not hundreds?

Answer 28

@pompeii you there? need your help again :D

Answer 29

b) no force on andrew

Answer 30

c) the bag wil float

Answer 31

Thanks shamim!

Answer 32

U r most welcome