[نيووزكـ كيمي*]

101 phy.
1- Assume that Young’s modulus is 1.5×10^10 N/m^2 for bone and that the bone will fracture if stress greater than 1.5×10^8 N/m^2 is imposed on it.
(a) What is the maximum force that can be exerted on the femur bone in the leg if it has a minimum effective diameter of 2.50 cm?
(b) If this much force is applied compressively, by how much does the 25.0cm-long bone shorten?

2- If the shear stress in steel exceeds 4×10^8 N/m^2 , the steel ruptures. Determine the shearing force necessary to shear a steel bolt 1.00 cm in diameter.


3- Calculate the absolute pressure at an ocean depth of 1 000 m. Assume the density of seawater is 1024 kg/m^3 and that the air above exerts a pressure of 101.3 kPa.

4- The small piston of a hydraulic lift has a cross-sectional area of 3m^2, and its large piston has a cross-sectional area of 200m^2. What force must be applied to the small piston for the lift to raise a load of 15.0 kN? (In service stations, this force is usually exerted by compressed air.)

5- A Ping-Pong ball has a diameter of 3.80 cm and average density of 0.084 g/cm^3. What force is required to hold it completely submerged under water?

6- A plastic sphere floats in water with 50.0 percent of its volume submerged. This same sphere floats in glycerin with 40.0 percent of its volume submerged. Determine the densities of the glycerin and the sphere.{extra}

7- A large storage tank, open at the top and filled with water, develops a small hole in its side at a point 16.0 m below the water level. If the rate of flow from the leak is equal to2.5×10^-3 m^3/min , determine (a) the speed at which the water leaves the hole and (b) the diameter of the hole.

8- The position of a particle is given by the expression x=(4m)cos(3بايtباي +), where x is in meters and t is in seconds. Determine (a) the frequency and period of the motion, (b) the amplitude of the motion, (c) the phase constant, and (d) the position of the particle at t = 0.250 s.

9- Liquid nitrogen has a boiling point of -195.81°C at atmospheric pressure. Express this temperature (a) in degrees Fahrenheit and (b) in kelvins.

10- A pair of eyeglass frames is made of epoxy plastic. At room temperature (20.0°C), the frames have circular lens holes 2.20 cm in radius. To what temperature must the frames be heated if lenses 2.21 cm in radius are to be inserted in them? The average coefficient of linear expansion for epoxy is 1.3×10^-4(c^0)^-1 .



11- Two concrete spans of a 250-m-long bridge are placed end to end so that no room is allowed for expansion (Fig. a). If a temperature increase of 20.0°C occurs, what is the height y to which the spans rise when they buckle (Fig. b). (The coefficient of linear expansion for concrete is12×10^-6(C°)^-1)? {extra}




12- The temperature of a silver bar rises by 10.0°C when it absorbs 1.23 kJ of energy by heat. The mass of the bar is 525 g. Determine the specific heat of silver.

13- A 50.0-g sample of copper is at 25.0°C. If 1 200 J of energy is added to it by heat, what is the final temperature of the copper? (the specific heat of copper is 387J/kg.c°)

14- A 1.50-kg iron horseshoe initially at 600°C is dropped into a bucket containing 20.0 kg of water at 25.0°C. What is the final temperature? (Ignore the heat capacity of the container), the specific heat of water is , and the specific heat of iron is448J/ kg.c°).



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