PHYS130 Chapter Notes - Chapter 7: Torero

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cerisegiraffe538

8 Sep 2015

School

University of Alberta

Department

Physics

Course

PHYS130

Professor

John Davis

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Energy is a scalar quantity associated with the state (or condition) of one or more object. Energy is a number that we associate with a system of one or more objects: kinetic energy k is energy associated with the state of motion of an object. The faster the object moves, the greater is its kinetic energy. When the object is stationary, its kinetic energy is zero: for an object of mass m whose speed v is well below the speed of light (e1) Work and kinetic energy: work w is energy transferred to or from an object by means of a force acting on the object. Energy transferred to the object is positive work, and energy transferred from the object is negative work. Work and kinetic energy: to calculate the work a force does on an object as the object moves through some displacement, we use only the force component along the object"s displacement.

Related Questions

1. Can work be done on a system if there is no motion?

A) Yes, if an outside force is provided B) Yes, since motion is only relative C) No, since a system which is not moving has no energy D) No, because of the way work is defined

2. The quantity 1/2 mv 2 is

A) the power supplied to the object by the force B) the work done on the object by the force C) the kinetic energy of the object. D) the potential energy of the object.

3. If you push twice as hard against a stationary brick wall, the amount of work you do

A) doubles. B) is cut in half C) remains constant but non-zero D) remains constant at zero

4. If the net work done on an object is positive, then the object's kinetic energy

A) increases. B) decreases C) remains the same D) is zero

5 A force of 20 N moves an object in the direction of the force. The work done when the object moves from 2.0 to 4.0 m is o A) 20 J OB) 40 J oC) 60 J D) 80 J

is defined as $K=(1/2)mv^2$ . It seems reasonable to say that the speed of an object--and, therefore, its kinetic energy--can be changed by performing work on the object. In this problem, we will explore the mathematical relationship between the work done on an object and the change in the kinetic energy of that object.

Let us now consider the situation quantitatively. Let the mass of the sled be and the magnitude of the net force acting on the sled be. The sled starts from rest.

Consider an interval of time during which the sled covers a distance

and the speed of the sled increases from

. We will use this information to find the relationship between the work done by the net force (otherwise known as the network) and the change in the kinetic energy of the sled.

Find the net force

acting on the sled.

Express your answer in terms of someor all of the variables

, and

Find the net work

done on the sled.

Express your answer in terms of someor all of the variables

is defined as $K=(1/2)mv^2$ . It seems reasonable to say that the speed of anobject--and, therefore, its kinetic energy--can be changed byperforming work on the object. In this problem, we willexplore the mathematical relationship between the work done on anobject and the change in the kinetic energy of that object.

Let us now consider the situationquantitatively. Let the mass of the sled be and the magnitude of the net force acting on the sled be. The sled starts from rest.

Consider an interval of time duringwhich the sled covers a distance

and the speed of the sled increases from

. We will use this information to find the relationshipbetween the work done by the net force (otherwise known as thenet work) and the change in the kinetic energy of thesled.

Find the net force

acting on the sled.

Express your answer in terms of someor all of the variables

, and

Find the net work

done on the sled.

Express your answer in terms of someor all of the variables

and

graywildebeest386

Two identical objects A and B move on a one-dimensional,horizontal air track. Object B initially moves to the right withspeed Vo. Object A initially moves to the right with speed 3Vo, sothat it collides with object B. Friction is negligible. Exress youranswers to the following in terms of M and Vo.

a) Determine the total momentum of the system of the twoobjects.

b) A student predicts that the collision will be totallyinelastic (the objects stick together on collision). Assuming thisis true, determine the following for the two objects immediatelyafter the collision.

i)the speed

ii) the direction of motion (left orright)

When the experiment is performed, the student is surprised toobserve that the obbjects separate after the collision and thatobject B subsequently moves to the right with a speed of 2.5Vo.

c) Determine the following for object A immediately after thecollision.

i)the speed

ii) the direction of motion (left or right)

d) determine the kinetic energy dissipated in the actualexperiment.

PHYS130 Chapter Notes - Chapter 7: Torero

PHYS130 Full Course Notes

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