Question

Please help!
A bridge with mass 9000. kg supports a truck with mass 3000. kg that is stopped in the middle of the bridge. What mass (in kg) must each pier of the bridge support?

= (9000 kg + 3000 kg) / 2
= 6000 kg

If the truck in the preceding problems stops 9.00 m from the northern end of the 32.0-m bridge, what mass (in kg) must the northern pier of the bridge support?

F1 + F2 = (9000 kg * 9.8 m/s^2) + (3000 kg * 9.8 m/s^2)
F1 + F2 = 88200 + 29400
F1 + F2 = 117,600 N

F1 (32.0 m) = (88200 N) (????? m) + (29400 N) (9.00 m)

@nikato @michele_Laino @lightgrav @radar @Greg_D @peachpi

the answers are suppose to be 5220 kg, 6580 kg

Answer 1

I tried this last night. Got the same numbers you did. 5220 kg doesn't even make sense for the first part because it's not enough support. The part you're missing for the 2nd part is 16 m. Weight acts at the center of the bridge, then you can solve for F1.

Answer 2

@peachpi, yeah the answer for the first problem is 6000 kg, but there are 2 asnwers for the second problem... I need help with the second one only

Answer 3

Is there another question for the 2nd problem?

Answer 4

They only ask for mass as far as I can tell

Answer 5

they are asking for the mass of the northern pier of the bridge.... so I don't know which answer it is or how you get the answers