Physics-Midterm-Exam 2016 Assignment

Physics-Midterm-Exam 2016
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Physics Midterm Exam 1
1 Use at least two to three completed content related sentences to explain why physics is considered the basic science. Provide at least one example to explain how physics relates to other sciences.
Physics is a branch of science that deals with the study of principles that govern the physical world (matter). Forces, momentum, energy and other concepts of physical situations that affect matter are also studied. The matter is basic and common in this physical world.
The matter is studied in various forms in astronomy as celestial bodies, in biology as cells, in chemistry as atoms. In all these cases forces, momentum and energy are studied in these other branches of science related to the forms of matter in the study.
1 You do work on something when you lift if against gravity. Explain how work relates to gravitational potential energy using at least two complete content related sentences. If the lifted object is released, describe the change in energy. Be sure to define all terms used in both questions.
Gravitational potential energy is the energy of a body due to its position(height). It increases with increase in height. This particular form of energy is not at work but in a stored state. After release, there is the conversion of the stored energy into working (kinetic energy).
Kinetic energy is the energy due to a body in motion (velocity). The total potential energy is equal to the kinetic energy since energy cannot be destroyed nor created but change into different forms.
2 Regarding momentum change, explain why it is best to “give” when catching a baseball. Provide at least TWO other examples of situations in which you want “give.”
As opposed to catching the ball whereby one has to stop the ball in a very short time the impulsive force on the hand can be painful if the force applied is high. Hence to give is a much more tolerable role in baseball than to catch.
Examples of “give,” passing the rugby ball to a mate or boxing competition.
3 A boy fires a table tennis launcher. Briefly describe the forces and impulses on the launcher and the ball. Explain which has momentum. Explain which is moving faster. Be sure to use at least 3 to 4 complete content related sentences.
There are three main forces involved this include action, reaction, and impulsive force.
The action force applied on the ball by the launcher, in this case, is much greater than the reaction of the ball to the launch. Hence this difference in action and reaction forces lead to the launch of the ball. The impulsive force is the change of momentum of the ball from rest to motion in the unit time of contact.
4 Write 4 to 5 sentences about what Chapter 1 says about the early scientists from Aristotle to Galileo thought about the nature of motion. (Hint: Need to include Aristotle, Galileo, and Copernicus.
Aristotle stated that an object would continue to be in motion if the force acting on it was continuous; he divided motion into natural and violent motion. Both Aristotle and Copernicus applied their knowledge of motion in determining the movement of “heavenly bodies.” Galileo’s greatest contribution to science was to disapprove Aristotle’s theory of an object will continue to be in continuous motion if the force acting on it was continuous. Instead, Galileo proved that an object was to be in continuous motion if only friction was absent.
5 Suppose you are on an airplane moving at high speed. If you flip a coin straight up, it will land in your lap rather than a great distance behind you. Explain why this is true and include any laws that help prove your point. Your answer should be at least 3 to 4 complete content related sentences.
The setup above obeys the first Newton’s law that is, an object at rest remains at rest, and an object in motion will remain in motion with the same speed and the same direction unless acted upon by an unbalanced force. Both the coin and the person flipping the coin are in the same motion at the same speed, hence are said to be in a state of inertia.
6 What is terminal speed? When a skydiver has reached terminal speed, what is the resistance equal to? What is the skydiver’s acceleration? Be sure to use at least 3 to 4 complete content related sentences.
When a free falling object accelerates to a maximum speed due to friction the maximum attainable speed during this fall is referred to as Terminal speed. The skydiver accelerates with the gravitational acceleration of 9.8m/s. The resistance force is equal to the multiplication of acceleration and mass of the skydiver.
7 A force is a push or a pull. Newton’s third law further defines the meaning of force. Be sure to explain using at least 3 to 4 complete content related sentences.
The third Newton's law states that for every action in nature, there is an equal opposite reaction. The action is attributed to acting as a pull whereas the reaction as a push. This shows force can be as a result of an action or reaction.
8 The sun radiates about 3.6 x 1026 joules of energy each second. How much mass does the loss each second? Show all of your work and be sure all numbers must be identified and explain in your work.
E = mc² where E is energy from the radiation, m is the mass, c is the speed of light
hence m = E/c^2
= (3.6x10^26)/(3×10^8)
= 12x 10^17 kg
9 Provide the time dilation equation found in Section 15.4 of the text. Explain each step of the derivation.
714375-276860ctct
ct0
vt
c is the speed of light
t is the time on earth
t0 is the time on the particular object
v is the velocity of the object.
(ct0)2 + (vt)2 = (ct)2
c2t02 + v2t2 = c2t2
put like terms together
c2t02 = v2t2 +c2t2
c2t02 = t2 (v2 +c2)
t2 = c2t02/(v2 +c2)
t2 = c2t02/ c2 (1+(v2 / c2 )) then divide all through by c2
t2 = t02/ (1+(v2 / c2 )) find the square root of the time t
t = t0/ √(1+(v2 / c2 ))
10 You sit at the outer rim of a Ferris Wheel that rotates two revolutions per minute (RPM). What would your rotational speed be if you were instead clinging to a position halfway from the center to the outer rim? Be sure to provide at least 3 to 4 complete content related sentences and show any work needed to support your answer.
2πN/60 is used to convert a number of revolutions per minute to rotational velocity.
ω = 2πN/60
where ω is rotational velocity π is 3.142 and N is the number of revolution.
ω =(2*3.142*2)/60
= 0.2094 Rad/s this is the speed at the outer rim of the Ferris wheel,0
The rotational speed halves due to the halving of the radius of rotation hence reduction in distance covered but the same time taken as at the outer rim.
Therefore, the speed at the halfway is 0.2094/2 = 0.1047 Rad/s
At the outer edge of a rotating space habitat, 130 m from the center, the rotational acceleration is g. What is the rotational acceleration at a distance of 65 m from the center of the habitat? Be sure to show all work and steps to support your answer.
Solution
Case 1 Case 2
The radius = 130m , The radius = 65m
The rotational acceleration = g The rotational acceleration = x
Then, let’s assume that the linear acceleration is maintained constant in both cases. Th...