* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download POP4e: Ch. 1 Problems
Survey
Document related concepts
Specific impulse wikipedia , lookup
Classical central-force problem wikipedia , lookup
Mass in special relativity wikipedia , lookup
Newton's laws of motion wikipedia , lookup
Speeds and feeds wikipedia , lookup
Faster-than-light wikipedia , lookup
Center of mass wikipedia , lookup
Work (physics) wikipedia , lookup
Kinetic energy wikipedia , lookup
Centripetal force wikipedia , lookup
Hunting oscillation wikipedia , lookup
Variable speed of light wikipedia , lookup
Transcript
PHYS-2325: University Physics-I HOMEWORK PROBLEMS Fall-2011 Ch-8 Chapter 8: CONSERVATION OF ENERGY Hand in your solutions in class in the lecture period after which the chapter is completed. Show the equations and calculations, and box your answer. Be sure to include the units. NOTE: Any four questions from this HW will be graded, and the marks for this HW will be based on these only. 1 A 2.5-kg object suspended from the ceiling by a string that has a length of 3.0 m is released from rest with the string 50° below the horizontal position. What is the tension in the string at the instant when the object passes through its lowest position? 2 A 0.3-kg ball is thrown from the top of a 30-m tall building (point A) at an unknown angle above the horizontal. As shown in the figure, the ball attains a maximum height of 10 m above the top of the building before striking the ground at point B. If air resistance is negligible, what is the value of the kinetic energy of the ball at B minus the kinetic energy of the ball at A (K B - KA)? 3 (8.3) A bead slides without friction around a loop-the-loop. The bead is released from a height h = 3.50R. What is its speed at point A? PHYS-2325: University Physics-I Fall-2011 Ch-8 4 (8.4) A child of mass m = 25.0 kg is starts from point A and slides on the frictionless track shown in the figure. Determine his speed at points B and C and the net work done by the gravitational force as he moves from A to C. 5 (8.32) A 500-kg elevator starts from rest. It moves upward for 4.0 s with constant acceleration until it reaches its cruising speed of 1.5 m/s. What is the average power of the elevator motor during this time interval? 6 (8.7) Two objects are connected by a light string passing over a light, frictionless pulley as shown in Figure P8.7. The object of mass 5.00 kg is released from rest. Using the isolated system model, determine the speed of the 3.00-kg object just as the 5.00-kg object hits the ground. PHYS-2325: University Physics-I Fall-2011 Ch-8 7 (8.19) The coefficient of friction between the 3.00-kg block and the surface in Figure P8.19 is 0.300. The system starts from rest. What is the speed of the 5.00-kg ball when it has fallen 2.0 m? 8 (8.21) A 3.00-kg block is set into motion up an inclined plane with an initial speed of 8.00 m/s. The block comes to rest after traveling 3.00 m along the plane, which is inclined at an angle of 30.0° to the horizontal. For this motion, determine the coefficient of kinetic friction. 9 A 10-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 700 N/m). The block is initially at rest at its equilibrium position when a force (magnitude P = 80 N) acting parallel to the surface is applied to the block, as shown. What is the speed of the block when it is 10 cm from its equilibrium position? PHYS-2325: University Physics-I Fall-2011 Ch-8 10 A 4.0-kg mass is projected from the edge of the top of a 15-m tall building with a velocity of 18 m/s at some unknown angle above the horizontal. Disregard air resistance and assume the ground is level. What is the kinetic energy of the mass just before it strikes the ground? 11 A 1.8-kg block sliding on a rough horizontal surface is attached to one end of a horizontal spring (k = 150 N/m) which has its other end fixed. If this system is displaced 25 cm horizontally from the equilibrium position and released from rest, the block first reaches the equilibrium position with a speed of 2.0 m/s. What is the coefficient of kinetic friction between the block and the horizontal surface on which it slides? 12 A 3.0-kg mass is projected vertically upward from ground level with an initial speed of 30 m/s. The mass rises to a maximum height of 35 m above ground level. How much work is done on the mass by air resistance between the point of projection and the point of maximum height? PHYS-2325: University Physics-I Fall-2011 Ch-8 13 The two masses in the figure are released from rest. After the 3.0-kg mass has fallen 1.4 m, it is moving with a speed of 3.2 m/s. How much work is done during this time interval by the frictional force on the 2.0 kg mass? 14 A champion athlete can produce one horsepower (746 W) for a short period of time. If a 60-kg athlete were to bicycle to the summit of a 600-m high mountain while expending power at this rate, she would reach the summit in ____ seconds.