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work and power

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Wize University Physics Textbook (Master) > Work and Energy

Power

3 Activities

Wize University Physics Textbook (Master) > Work and Energy

Mechanical Work (Basic)

3 Activities

Someone takes 11 minutes to walk up a hill 120m high. His weight is 550N.
(a) How much work did he do in climbing the hill?
(b) What power is developed by his muscles as he climbs?
(c) If he runs up the hill his muscles can exert 550 Watts. How long (in mins) will it take him to get to the top of the hill?
More Power Questions:
Practice: Power of a tow car
A tow car is towing a 900-kg car up on a 10∘10^{^{\circ}} hill with constant speed of 36 km/h. The hill is sandy and exerts constant friction force of 300 N on the car. How much power does the tow car supply to tow the car? Select the closest answer.
The motion of a 1.00-kg box along the x-axis is described by the function x(t)=2.0−t2+0.5t3x\left(t\right)=2.0-t^2+0.5t^3. Which choice correctly represents the power delivered to the box as function of time?
A) P(t)=4t−9t2+4.5t3P\left(t\right)=4t-9t^2+4.5t^3 B) P(t)=1.5t−5t2+3t3P\left(t\right)=1.5t-5t^2+3t^3
C) P(t)=−4t−3t2−4.5t3P\left(t\right)=-4t-3t^2-4.5t^3 D) P(t)=4+3t2+4.5t3P\left(t\right)=4+3t^2+4.5t^3
power
A motor raises a mass of 3 kg to a height h at a constant speed of 0.05 m/s. The battery which provides energy to the motor originally stores 4 J of energy, all of which can be used to lift the mass.
(a) What is the power developed in the motor?
(b) To what maximum height can the motor lift the mass using its stored energy?
Power
A motorbike engine can develop a power of 90000 W in order to keep a constant velocity of 30 m/s. What is the pushing force?
Power
(a) How much work is done in lifting an object that weighs 250N to a height of 4m? (b) At what rate is work done if the 250N object is lifted to a height 4m in 4s?
A 1500-kg kg car accelerates from 0 to 10 m/s in 5 s with negligible friction and air resistance. What is the average power delivered by the engine? (1 hp=746 W)\left(1\ hp=746\ W\right)
More Mechanical Work (Basic) Questions:
work done
A 70kg70kgman carries a 15kg15kgbox up a flight of stairs. If the angle of the stairs is 25°25\degreeand the man travels a total distance of 14m14m, how much work does he do to the box? How much work does he do in total?
Practice: Work done by gravity
When would the work done by gravity on a simple pendulum be negative?
Forces: Work- wagon on slope
A 20kg wagon rests on an inclined plane with angle 30°. The wagon is pulled by a 200N tension force along the plane and is displaced by 2 m. The coefficient of kinetic friction between the surfaces is 0.30.
A 70kg70kgman carries a 15kg15kgbox up a flight of stairs.
a) If the angle of the stairs is 25°25\degreeand the man travels a total distance of 14m14m, how much work does he do to the box?
b) How much work does he do in total?
What is the work done by tension on the mass in a simple pendulum?
When would the work done by gravity on a simple pendulum be negative?
Consider a simple pendulum that is just beginning to fall after reaching one of its highest positions. In this moment, is the work done by gravity positive, negative, or zero?
An object moving along x-axis is acted upon by a variable force F(x)F\left(x\right) . How much work does the force do on the object as the object moves from x=0 to x=16 m?
You're running up the stairs because you are late for class. Which of the following statements about the work done by gravity on you?
Tom is holding a book and moving it horizontally. What is true about the work Tom is performing on the book?
Work on wagon
A 20kg wagon rests on an inclined plane with angle 30°. The wagon is pulled by a 200N tension force along the plane and is displaced by 2 m. The coefficient of kinetic friction between the surfaces is 0.30.
a) Draw a free-body diagram for the wagon.
b) Find the work done by each force on the wagon.
work done by force of friction
A 5 kg block is moved up a 30 degree incline by a force of 50 N, parallel to the incline. The coefficient of kinetic friction between the block and the incline is .25. How much work is done by the 50 N force in moving the block a distance of 10 meters? What is the total work done on the block over the same distance?
work done
A ball is connected to a rope and swung around in uniform circular motion. The tension in the rope is measured at 10 N and the radius of the circle is 1 m. How much work is done in one revolution around the circle?
Work done
A person is holding a bucket by applying a force of 10N. He moves a horizontal distance of 5m and then climbs up a vertical distance of 10m. Find the total work done by him?
Work done by friction
When a body slides against a rough horizontal surface, the work done by friction is ___________
Work done
When a body falls freely under gravity, then the work done by the gravity is ___________
work done
A 70kg70kgman carries a 15kg15kgbox up a flight of stairs. If the angle of the stairs is 25°25\degreeand the man travels a total distance of 14m14m, how much work does he do to the box? How much work does he do in total?
A 100-grams steel ball is revolving around a vertical post by a string, at constant pace of once every second. The circle has radius 30 cm. Which statement(s) is correct for one full revolution?