30 POINTS TO ANYONE WHO CAN DO THIS FOR ME. I FORGOT ABOUT IT AND IT'S DUE SOON PLEASE PLEASE PLEASE
Also GUESS stands for Given info, Understand (basically what are they asking you to do), Equation (formula), Substitute (fill in the numbers into the formula), and Solve

3. On the three diagrams below, draw vectors (arrows) indicating the direction of the velocity, acceleration, and net force for an object is moving in a circle at a constant speed in a 'counter-clockwise fashion.'

Velocity Acceleration Net Force

4. Four objects are attached to a 1-meter long string at various locations - shown to the right. The string is held at one end and twirled in a circle. The object, if any, that moves with the greatest speed is object ___.

5. An eraser is tied to a string and held by a physics teacher. The eraser is whirled in a circle at constant speed. A 'Bird's eye' view of the circle is shown in the diagrams below. If the teacher lets go of the string when the eraser is at the indicated position, then which one of the paths best represents the motion of the eraser?

6. In order to keep an object moving in a circle, an (inward or outward) pointing force is required, which is called the (centripetal or centrifugal) force.

7. A car makes a left-hand turn. The front-seat passenger claims that she feels a sensation of being pulled outwards. This is best explained by the fact that .
a. the passenger has a natural tendency to move tangent to and out of the circular path
b. while there may be a net inward force, there is still an outward force upon the passenger
c. there is a centrifugal force which pushes the person 'out the door'
d. there is a centripetal force pushing the person 'out the door'
e. the driver is not enjoying the passenger's company
8. An eraser is tied to a string and whirled in a horizontal circle at a constant speed. Inertia is the natural tendency of the eraser to resist changes in its state of motion. This means that the eraser ___.
a. is not accelerating since it is maintaining the same circular path at a constant speed
b. would naturally move tangent to the circle if the string is released
c. will continue along its circular path if the forces on it suddenly become balanced
d. would require an unbalanced force in order to leave the circle and continue tangent to it
e. is experiencing a balance of forces - the inward and the outward force balance each other
9. Suppose you go with your friend on a roller coaster ride. After the ride, your friend describes the 'awesome outward pull on the second loop.' Such a statement only proves that your friend .
a. is a coaster fanatic
b. truly experienced a centrifugal force
c. has consumed way too much cotton candy
d. knows that riders moving through circles experience outward forces
e. might not understand the physics of circular motion

10. A toy electric train moving at constant speed on a circular track that has a radius of 1.2 meters goes around the track every 8 seconds. What is the speed of the train?
G U E S S

11. Zach drives his car around a circular section of a road having a radius of 50 meters at a constant speed of 20 m/s. What is the acceleration of Zach’s car?
G U E S S

12. A roller coaster car loaded with passengers, has a mass of 500. kg; the radius of curvature of the track at the bottom point of a dip is 12.0 m. The vehicle has a speed of 18.0 m/s at this point. Calculate the net force on the roller coaster.
G U E S S

3.1 Work and Power
1. What are the units of work? What are the units of power?

2. Does walking a mile or running a mile require more work? Which one requires more power? Explain.

3. Which requires more work; walking up one set of stairs or three sets of stairs at the same speed? Which requires more power?

4. If a person climbs one set of stairs in 4 seconds, and then climbs two sets of stairs in the same time; which requires more work? Which requires more power?

5. A small child and an adult climb a set of stairs at the same time? Who does more work? Who exerts more power?

6. A force of 1200 Newtons is needed to push a car across a lot. Two students push the car 10 meters. How much work is done?
G U E S S

7. At a tractor pull, one machine has a run that produces 45,000 Joules of work in 3 seconds. How much power was exerted by this tractor?
G U E S S

8. How much work is done by a 1500 watt electrical motor is 7.5 seconds?
G U E S S