# Solids and Fluids

kamoey
Some of the problems, I really don't know how to even set up the problem. I don't want an answer for them, but I need an idea where to start.

1. Gauge pressure in both tires = 690 kPa.
Bike and the riders mass = 90.0 kg.
Find area of contact of each tire with the ground if each tire supports half the total weight.
I read the section that this problem corresponse to and could not figure out where to start.

3. Boat overloaded such that water level is 1.0cm below top of boat.
Total lenght= 4.5m
height= .3m
width= 2.0m

Find combinded mass of people and boat.

I'm not sure how to to this one.
I drew a FBD and got...
Force of boat=mg
Density of water x volume of object x gravity= mg
(1000kg/m^3)(2.61m^3)=mass
?=2610 kg

4. Irregularly shaped piece of metal
weight=.882 N. When submerged in water irregual object is suspended from scale rading .735 N.
Find volume and density of object.

Doc Al
Mentor
Originally posted by kamoey
1. Gauge pressure in both tires = 690 kPa.
Bike and the riders mass = 90.0 kg.
Find area of contact of each tire with the ground if each tire supports half the total weight.
I read the section that this problem corresponse to and could not figure out where to start.
Think Pressure = Force/Area; the force must be enough to support the bike + rider.

3. Boat overloaded such that water level is 1.0cm below top of boat.
Total lenght= 4.5m
height= .3m
width= 2.0m

Find combinded mass of people and boat.

I'm not sure how to to this one.
I drew a FBD and got...
Force of boat=mg
Density of water x volume of object x gravity= mg
(1000kg/m^3)(2.61m^3)=mass
?=2610 kg
Assuming the boat is rectangular, you got it.

4. Irregularly shaped piece of metal
weight=.882 N. When submerged in water irregual object is suspended from scale rading .735 N.
Find volume and density of object.
The scale reading is the force that the scale must pull up to support the object. So, consider the forces acting on the object when it's submerged: The scale is pulling up, the bouyant force (water) is pushing up, and the weight is pulling down. These forces must balance.