18. [-/10 Points] DETAILS SERPSE10 14.8.OP.031.MI. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) A hypodermic syringe contains a medicine with the density of water (see figure below). The barrel of the syringe has a cross-sectional area A = 2.20 x 10-5 m , and the needle has a cross-sectional area a = 1.00 x 10-8 m2. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force F of magnitude 2.60 N acts on the plunger, making medicine squirt horizontally from the needle. Determine the speed of the medicine (in m/s) as it leaves the needle's tip. m/s (b) What If? Magnetic injection devices are now being tested for needle-free delivery of drugs through the skin. These devices propel the liquid medicine to near the speed of sound. If we wished to duplicate this type of delivery with the syringe shown in the figure, what force F would be required (in N) to deliver the medicine at a speed of 341 m/s through the needle? IN Need Help? Read It Master It 19. [-/10 Points] DETAILS SERPSE10 14.A.OP.032. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) Calculate the absolute pressure at an ocean depth of 1,025 m. Assume the density of seawater is 1,030 kg/m and the air above exerts a pressure of 101.3 kPa. Pa (b) At this depth, what is the buoyant force on a spherical submarine having a diameter of 5.30 m? Need Help? Read It Watch It 20. [-/10 Points] DETAILS SERPSE10 14.A.P.037. MY NOTES ASK YOUR TEACHER Evangelista Torricelli was the first person to realize that we live at the bottom of an ocean of air. He correctly surmised that the pressure of our atmosphere is attributable to the weight of the air. The density of air at 0C at the Earth's surface is 1.29 kg/m3. The density decreases with increasing altitude (as the atmosphere thins). On the other hand, if we assume that the density is constant at 1.29 kg/m up to some altitude h, and zero above that altitude, then / would represent the depth of the ocean of air. (a) Use this model to determine the value of h that gives a pressure of 1.00 atm at the surface of the Earth. km (b) Would the peak of Mt. Everest rise above the surface of such an atmosphere? O Yes O No Need Help? Read It21. [-/10 Points] DETAILS SERPSE10 14.A.OP.040. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The figure below shows a spring scale and a platform scale. A beaker containing linseed oil rests on the platform scale and a brass block is attached to the spring scale and submerged in the fluid. The mass of the beaker, fluid, and block are respectively mp = 1.05 kg, my = 2.02 kg, and mbik = 2.02 kg and the density of linseed oil and brass are respectively 929 kg/m and 8,520 kg/m3. Determine the equilibrium reading (in N) for (a) the spring scale and (b) the platform scale. (a) the spring scale N (b) the platform scale IN Need Help? Read It 22. [-/10 Points] DETAILS SERPSE10 14.A.OP.042. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A hydraulic brake system consists of the brake pedal, a master cylinder, a brake cylinder, a brake shoe, and a wheel drum (see the figure below). When the driver exerts a force Fake on the pedal, the result is a force of friction f on the wheel drum and hence a frictional torque about the axle. The master cylinder piston's cross-sectional area A is 1.80 cm , while the brake cylinder piston's cross-sectional area Abc is 6.40 cm". The coefficient of friction between the brake shoe and the drum is 0.500, and the wheel drum has a radius of 40.3 cm. Determine the frictional torque about the axle when the force exerted on the brake pedal is 46.7 N. (Give the magnitude of your answer in N . m.) Wheel drum Pedal Shoe Master Brake cylinder cylinder N . m Need Help? Read It