A block of mass 0.85 kg and density 600 kg/m3 is forced under the surface of the water by means of a spring (k = 90.0 N/m) that is fixed to the bottom of the container. How much does the spring stretch? (the density of water is 1000 kg/m3).

A 7.20 kg rock whose density is 4900 kg/m3 is suspended by a string such that half of the rock's volume is underwater. What is the tension in the string?

Water (density = 1 x l03 kg/m3) flows at 13.6 m/s through a pipe with radius 0.05 m. This same pipe goes up to the second floor of the building, 4 m higher, and the pressure remains unchanged. What is the speed of the water flow on the second floor?

the plunger and the needle of a hypodermic syringe have areas of 0.5 cm^2 and 0.0006 cm^2, respectively. To inject a vaccine, a nurse pushes the plunger with a force of 5.5 N. What pressure is transmitted into the vaccine?

The density of ice is 917 kg/m3, and the density of sea water is 1025 kg/m3. A swimming polar bear climbs onto a piece of floating ice that has a volume of 6.29 m3. (a) What is the weight of the heaviest bear that the ice can support without sinking completely beneath the water? To verify her suspicion that a rock specimen is hollow, a geologist weighs the specimen in air and in water. She finds that the specimen weighs twice as much in air as it does in water. The density of the solid part of the specimen is 5.42 × 103 kg/m3. (b) What fraction of the specimen’s apparent volume is solid?

A helium-filled balloon, whose envelope has a mass of 0.25 kg, is tied to a 2.0-m-long,  0.050-kg string. The balloon is spherical with a radius of  0.40 m. When released, it lifts a length h of the string and then remains in equilibrium. Hint: Only that part of the string above the floor contributes to the load being supported by the balloon. d. If the density of air is ρ_{air}=1.29 kg/m^3 and the density of Helium is ρ_{He}=0.179 kg/m^3, find h.

45. ssm An 81-kg person puts on a life jacket, jumps into the water, and floats. The jacket has a volume of 3.1 × 10-² m² and is completely sub- merged under the water. The volume of the person's body that is under water is 6.2 x 10-²m³. What is the density of the life jacket?

A wooden raft has a mass of 50 kg. When empty it floats in water (density 1000 kg/m3) with 69% of its volume submerged. What mass of sand can be put on the raft without it sinking?

A weed trimmer for yard work has a rotating head which consists of a spool of monofilament line, with a strand of line that extends out from the edge. The spool has an inner diameter of 3.00 cm and an outer diameter of 18.0 cm, and a mass of 100 g. The strand has a length of 16.0 cm. The monofilament line has a linear density of 10.0 g/m. 16.0 cm- Need Help? 3.00 cm (a) When switched on, the trimmer speeds up from 0 to 2.500 rev/min in 0.225 s. What average power (in W) is delivered to the head by the trimmer motor while it is accelerating? (Round your answer to at least one decimal place.) -18.0 cm- (b) When the trimmer is cutting weeds, it spins at 2,100 rev/min and the weeds exert an average tangential force of 9.15 N on the outer end of the line, which is still at a radial distance of 16.0 cm from the outer edge of the spool. What is the power (in W) delivered to the head under load? W Read

a diving sphere has a mass of 2.05x10^5 kg and an external diameter of 12.0 meters. the sphere initially floats on the surface of the ocean. the density of the sea water is 1025 kg/m^3. a large anchor is then attached to the sphere and it sinks to the ocean floor at a depth of 1.49 km. what is the buoyant force felt by the submerged sphere? what is the tension in the anchor cable?