Given
[link] about how much force does the rocket engine exert on the 3.0-kg payload?
Distance traveled with rocket engine firing (m)
Payload final velocity (m/s)
500
310
490
300
1020
450
505
312
150 N
300 N
450 N
600 N
(b)
You have a cart track, a cart, several masses, and a position-sensing pulley. Design an experiment to examine how the force exerted on the cart does work as it moves through a distance.
Look at
[link] (c). You compress a spring by
x , and then release it. Next you compress the spring by 2
x . How much more work did you do the second time than the first?
Half as much
The same
Twice as much
Four times as much
(d)
You have a cart track, two carts, several masses, a position-sensing pulley, and a piece of carpet (a rough surface) that will fit over the track. Design an experiment to examine how the force exerted on the cart does work as the cart moves through a distance.
A crane is lifting construction materials from the ground to an elevation of 60 m. Over the first 10 m, the motor linearly increases the force it exerts from 0 to 10 kN. It exerts that constant force for the next 40 m, and then winds down to 0 N again over the last 10 m, as shown in the figure. What is the total work done on the construction materials?
500 kJ
600 kJ
300 kJ
18 MJ
(a)
Section summary
Work is the transfer of energy by a force acting on an object as it is displaced.
The work
that a force
does on an object is the product of the magnitude
of the force, times the magnitude
of the displacement, times the cosine of the angle
between them. In symbols,
The SI unit for work and energy is the joule (J), where
.
The work done by a force is zero if the displacement is either zero or perpendicular to the force.
The work done is positive if the force and displacement have the same direction, and negative if they have opposite direction.
Conceptual questions
Give an example of something we think of as work in everyday circumstances that is not work in the scientific sense. Is energy transferred or changed in form in your example? If so, explain how this is accomplished without doing work.
Give an example of a situation in which there is a force and a displacement, but the force does no work. Explain why it does no work.
Describe a situation in which a force is exerted for a long time but does no work. Explain.
Problems&Exercises
How much work does a supermarket checkout attendant do on a can of soup he pushes 0.600 m horizontally with a force of 5.00 N? Express your answer in joules and kilocalories.
A 75.0-kg person climbs stairs, gaining 2.50 meters in height. Find the work done to accomplish this task.
(a) Calculate the work done on a 1500-kg elevator car by its cable to lift it 40.0 m at constant speed, assuming friction averages 100 N. (b) What is the work done on the lift by the gravitational force in this process? (c) What is the total work done on the lift?
(a)
(b)
(c) The net force is zero.
Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 2.0 gal of gasoline. Only 30% of the gasoline goes into useful work by the force that keeps the car moving at constant speed despite friction. (See
[link] for the energy content of gasoline.) (a) What is the magnitude of the force exerted to keep the car moving at constant speed? (b) If the required force is directly proportional to speed, how many gallons will be used to drive 108 km at a speed of 28.0 m/s?
Calculate the work done by an 85.0-kg man who pushes a crate 4.00 m up along a ramp that makes an angle of
with the horizontal. (See
[link] .) He exerts a force of 500 N on the crate parallel to the ramp and moves at a constant speed. Be certain to include the work he does on the crate
and on his body to get up the ramp.
A man pushes a crate up a ramp.
How much work is done by the boy pulling his sister 30.0 m in a wagon as shown in
[link] ? Assume no friction acts on the wagon.
The boy does work on the system of the wagon and the child when he pulls them as shown.
A shopper pushes a grocery cart 20.0 m at constant speed on level ground, against a 35.0 N frictional force. He pushes in a direction
below the horizontal. (a) What is the work done on the cart by friction? (b) What is the work done on the cart by the gravitational force? (c) What is the work done on the cart by the shopper? (d) Find the force the shopper exerts, using energy considerations. (e) What is the total work done on the cart?
(a)
(b) 0
(c) 700 J
(d) 38.6 N
(e) 0
Suppose the ski patrol lowers a rescue sled and victim, having a total mass of 90.0 kg, down a
slope at constant speed, as shown in
[link] . The coefficient of friction between the sled and the snow is 0.100. (a) How much work is done by friction as the sled moves 30.0 m along the hill? (b) How much work is done by the rope on the sled in this distance? (c) What is the work done by the gravitational force on the sled? (d) What is the total work done?
A rescue sled and victim are lowered down a steep slope.
Questions & Answers
I'm interested in biological psychology and cognitive psychology
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
effective communication can lead to improved outcomes in various settings, including personal relationships, business environments, and educational settings. By communicating effectively, individuals can negotiate effectively, solve problems collaboratively, and work towards common goals.
it starts up serve and return practice/assessments.it helps find voice talking therapy also assessments through relaxed conversation.
miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills