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Physics 1441 Section 001D

Final Exam Practice

You may use one equation sheet and a calculator. Please show your work and draw diagrams in order to get partial credit. Numerical values in problems are different for different student exams so don’t look for your answer on somebody else’s paper. In solving a problem (1) draw a good diagram (2) State the definitions or physical laws that you think are needed to solve the problem and (3) insert physical data and solve equations. Partial credit will be maximized by this process.

1. A delivery truck leaves a warehouse and travels 2.6 km north. The truck then makes a right turn and travels 1.33 km east before making another right turn and traveling 1.45 km south to arrive at it final destination. What is the magnitude and direction of the truck’s displacement from the warehouse?

2. A 4-kg block lies adjacent to the left of a 2-kg block and they both can move on a horizontal frictionless surface. The blocks are accelerated to the right by a +12-N force that pushes the larger block against the smaller one. Determine the force that the 2-kg block exerts on the 4-kg block (magnitude and direction).

3. A certain string just breaks when it is under 400 N of tension. A boy uses this string to whirl a 10-kg stone in a horizontal circle of radius of 10 m. The boy continuously increases the speed of the stone until the string breaks. At what tangential speed of the stone does the string break?

4. An engineer is asked to design a playground slide such that the speed that a child reaches at the bottom of the slide does not exceed 6.0 m/s. Determine the maximum height that the slide can be. Does this depend upon the shape of the slide? Ignore friction.

5. A 0.50-kg bomb is sliding along an icy pond (frictionless surface) with a velocity of 2.0 m/s to the west. The bomb explodes into two pieces. After the explosion, a 0.20-kg piece moves south at 4.0 m/s. What are the components of the velocity of the other 0.30-kg piece?

6. A circular disk of radius 2.0 m rotates with a constant angular acceleration of 20.0 rad/s2. What is the tangential acceleration of a point on the edge of the disk at an instant that its angular speed is 1.0 rev/s? Be careful about units.

7. A 50-kg rider on a moped of mass 75 kg is traveling with a speed of 20 m/s. Each of the two wheels of the moped has a radius of 0.2 m and a moment of inertia of 0.2 kg-m2. What is the total rotational kinetic energy of the two wheels?

8. A spring constant for the spring in a special cannon is 1800 N/m. In cocking the cannon, the spring is compressed 0.55 m. What is the initial speed of a 7.0-kg cannonball on the free end of the spring when it is released?

9. Using the value of atmospheric pressure at sea level, 1x105 Pa, estimate the total mass of the earth’s atmosphere above a 5-m2 area at the surface of the earth.

10. A solid object weighs 15 N in air and 13 N when submerged in water. Determine the density of the object.