Work by a Constant Force
Work-Energy & Kinetic
Gravity
Work & Power
100
The unit of work
What is a Joule?
100
You can increase the potential energy of a bow and arrow by
What is pulling the arrow back?
100
The formula for work done by gravity is
What is negative mass times gravity times delta y
100
The formula for power
What is Work Divided by Time.
200
The rate at which work is done
What is Power?
200
The formula to find kinetic energy
What is one-half times the mass times the velocity squared.
200
The cosine of your angle plus 90 degrees is also equal to
What is negative sine of your angle.
200
The unit for Power
What is Joule per Second or What is Watt?
300
Some children are practicing catching baseballs. The coach tosses the ball into the air and hits the ball with his bat. The ball travels nearly horizontally, directly at the short stop who manages to catch the line drive. Did the coach, via the bat, do any work on the ball as it was hit?
a) No, it travels nearly horizontally, and no work is done.
b) Yes, work was done on the ball because during the time the force acted on the ball, the bat and ball moved through some distance.
c) No, there was a force acting on the ball, but there was no displacement while the force was acting.
d) Yes, work was done on the ball because the force of gravity was acting on the ball while it was being hit.
e)No work was done on the ball because the ball flew even though the force was no longer acting on it.
What is work was done on the ball because during the time the force acted on the ball, the bat and ball moved through some distance.
300
Determine the amount of work done in firing a 2.0-kg projectile with an initial speed of 50 m/s. Neglect any effects due to air resistance.
a) 900 J
b) 1600 J
c) 2500 J
d) 4900 J
e) This cannot be determined without knowing the launch angle.
What is 2500 Joules
300
A person drops a ball from the top of a building while another person on the ground observes the ball's motion. Will these two people always agree on the ball's kinetic energy?
What is yes? Why?
300
You do 2000 J of work in 5 seconds. Your work is ...
What is 400 watts?
400
If a bug and a car collide, which one experiences the greater force
What is they both experience the same amount of force?
400
Which one of the following choices represents the largest kinetic energy?
a)Mars is moving in its orbit around the Sun.
b)A cyclist is racing in the annual Tour de France bicycle race.
c)A leaf falls from a tree.
d)A cheetah runs at its maximum speed to catch a fleeing zebra.
An oil tanker sails through the Panama Canal.
What is Mars is moving in its orbit around the Sun.
400
A satellite is in a circular orbit above the earth's surface. Why is the work done on the satellite by the gravitational force zero?
What is because the satellite remains at the same height? Meaning, Delta y is zero.
400
How much work is done on a vacuum cleaner pulled 3.0 meters by a force 50.0 N at an angle of 30 degrees?
What is 130 Joules?
500
This law states that energy can not be made or destroyed
What is the First Law of Thermodynamics
500
A high school baseball pitcher can typically throw a ball at 22 m/s. Professional baseball pitchers can throw the ball with twice that speed, but few others can. To see why this is the case, determine the difference in the kinetic energy of a baseball thrown at v m/s and one thrown at 2v m/s and express the difference as a percentage.
a) 50 %
b) 100 %
c) 200 %
d) 300 %
e) 400 %
What is 300%
500
An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the tension in the cable and the gravitational force. Which one of the following statements is true?
a) The work done by the tension force is zero joules.
b) The net work done by the two forces is zero joules.
c) The work done by the gravitational force is zero joules.
d) The magnitude of the work done by the gravitational force is larger than that done by the tension force.
e) The magnitude of the work done by the tension force is larger than that done by the gravitational force.
What is the net work done by the two forces is zero joules.
500
If a neighbor pushes a lawnmower four times as far as you do, but only exerts only half the force, which one of you does more work and by how much?
What is the neighbor and twice as much?