HELP WITH PHYSICS FINAL!!!!

General Physics I THE FINAL RACE TO THE FINISH! Summer I 2013

Show all your work! Box your answers, and submit the exam with exam questions (e.g. this copy). Non-
compliance with aforementioned instructions will result in a deduction of 7 points off the overall grade!
Remember your answers should use the meter-second-kilogram units. You will have to research certain
terminologies in this exam (e.g. A.U.). REMEMBER ALL YOUR ANSWERS MUST BE IN EITHER
SECONDS, METERS AND KILOGRAMS! If you have any questions, email me as soon as possible. The
exam is DUE AT THE BEGINNING OF CLASS! JUNE 28.

1. A 25.0 kg ball rolls off a 3.0 meter, frictionless ramp, inclined at 30.0º onto a level, frictionless floor for 25.5
seconds. Then it rolls up another frictionless ramp of equal degree and 3.5 meters in length. What is the potential
energy of the ball at part I (fig 1)? What is the kinetic energy of the ball at the part I/part II boundary? What is the
work done in part I and in part II? What is the total work done on the system from start to finish? What kind of
potential energy is described in part I? If the 2nd ramp in part III were only 2.5 m, at what velocity (remember,
speed and direction) will the ball leave the ramp? If instead you have a loop-d-loop that is as high as the 3.0 ramp
is above ground, what would be the necessary initial velocity to complete passing through the loop?

2. A 25.0 kg ball rolls along a flat, frictionless surface, and has to reach the end of the 5.5 meter frictionless ramp
elevated 1.5 meters (part II to part III in fig 2). What is the angle made with the horizontal (i.e. At what angle is
the ramp tilled)? What is the needed velocity to go up the ramp? When the ball stops at the end of the ramp, what
is its potential energy? What is the total work done on the system from part II to part III? Does this system
represent conservative or non-conservative forces?

3. A brick is on 45° incline (fig 3a). Draw the Free Body Diagram. What is the net force on the brick if it is
stationary? What must the coefficient of static friction (µs) be to have zero net work done on the block? If the
block is 125 kg, what is the work done by gravity, by friction and the net work on the block if it slides down for 5.0
seconds and assuming µk to be 1/8 that of µs? Starting at rest on a flat, frictionless surface, calculate the
acceleration needed to attain the same amount of work as the system above over a 10.5 second period.

4. Each object, starting from left to right, has a mass of 20.0 kg, 25.0 kg and 5.0 kg respectively. They are attached
by rope and pulled by an individual (see figure 4). Their unified acceleration is 5.5 m/s 2 in the x direction. What is
the horizontal force applied on the block system? What type of horizontal force is applied on all three blocks (e.g.
tensional, compressional, etc)? What is the horizontal force applied on m 3? What is the work done by all the
blocks if they all start from rest, and are accelerated with the force you calculated for 10.0 seconds? If there is a
220.0 N frictional force is applied to the system, will the system continue to accelerate? If so, by how much?
Explain your reasoning.

5. Calculate the moment of inertia for the following examples in figure 5 given r = 0.5 m and m = 500.0 kg. How
much rotational energy does each example have if ω = 120.0 rad/sec. If each example had translational motion
through space of 100.0 m/s, what would be the total kinetic energy of each example (NOTE: For 5f, R1 = 0.25 m
and R2 = 0.5 m)?

6. In figure 6 , what is the acceleration needed for the ball, initially at rest, to achieve an impulse of 50.0 N·s in 1/10
of a second (ball is hit by a bat) if the mass of the ball is 10.0 kg? What was the force applied? What was the ball’s
acceleration? This ball, now traveling with a final velocity gained from the previous problem, strikes head on a
stationary 12.0 kg ball, the result slows the striking ball down to

1.5 m/s

. What is the other ball’s velocity after the
collision? What type of collisions is this?

7. If a 1.1×1011 N force is applied on each 100.0 m cylinder of aluminum, brass and steel with a radius of 10.0 m
(figure 8 ). Find the final length of each cylinder. Create a 1000.0 kg, cylindrical boat made of steel such that it is
able to hold a 1500.0 kg, 1.5 m3 container. Of this same boat, what is the pressure that the bottom of the boat
exerts on the water (3 Extra Credit points: What are the three principle components of steel?)

8. A corridor of fluid exists such that there is a variation in densities (fig 9). A mini-probe is then placed at one end of
the corridor that is 0.2 m wide and always has the same velocity as the fluid for which it is in. Calculate the
velocities of the probe @ a,b & c. Calculate the necessary aperture at a, b & c such that the probe maintains the
same velocity throughout. What principle(s) are you using to solve this problem? Redraw the corridor (tube)
according to your calculations from the previous problem.

9. A ball weighing 500.0 N hangs by two cables (figure 10, not completely drawn to scale). Both cables are at 45°
from the ceiling. Draw the ball’s Free Body Diagram. What is the tension in each cable? What are the vertical and
horizontal components of force in cable 2? If the mass were to increase by 50%, what would the tensions be in the
cables? If and updraft of 25 N acted on the 500.0 N ball, what would be the new tensions in the cable?

General Physics I THE FINAL RACE TO THE FINISH! Summer I 2013

10. For figure 11a, what is the mass of m3? In figure 11b , what would be the torque if object? In table 1, plot the force
vs. distance values of a moving object. Calculate the work done by this object. Based on table 1, what was the final
velocity of this object, which started a rest? Then, calculate the torques for each angle in figure 12. What must the
moment arm length be in order to get the same torque (and force) as the first case, but have the force applied at an
angle of 45°?

Figure 1

Figure 2

Figure 3

General Physics I THE FINAL RACE TO THE FINISH! Summer I 2013

Figure 3a

Figure 4

General Physics I THE FINAL RACE TO THE FINISH! Summer I 2013

Figure 5

Table 1: Force – Distance data of a 10.0 kg object
Force (N) Distance (m)

0 0
5 5

10 10
15 15
15 20
15 25

General Physics I THE FINAL RACE TO THE FINISH! Summer I 2013

Figure 8

steel brass Aluminum

Figure 1

F = 1.1×1011 N

100.0 m

Figure 9

A: 1.5 g/cm3

B: 2.3 g/cm3

C: 1.0 g/cm3

1.5 m/s

General Physics I THE FINAL RACE TO THE FINISH! Summer I 2013

Figure 11b

Figure 11a

Figure 12

Figure 10