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Objects with masses of 157 kg and 768 kg are separated by 0.342 m. A 28.7 kg mass is placed midway between them. 0.342 m b b 157 kg 28.7 kg 768 kg Find the magnitude of the net gravitational force exerted by the two larger masses on the 28.7 kg mass. The value of the universal gravitational constant is 6.672 × 10−11 N · m2 /kg2 .
If a kettle uses 0.25 kW and you run the kettle every morning for 10 minutes. How much energy are you using in a week?
a force acts on a 2kg mass and gives it an acceleration of 3 m/s^2. What acceleration is produced by the same force when acting on a mass of 4kg?
A 10 kg block of metal measuring 12 cm x 10 cm x 10 cm is suspended
from a scale and immersed in water. The 12 cm dimension is vertical, and
the top of the block is 5 cm below the surface of the water as shown in the
figure.
(a) What are the forces acting on the top and on the bottom of the block?
(b) What is the reading of the spring scale? 86.2 N
(c) Show that the buoyant force equals the difference between the forces
at the top and bottom of the block.
a man weighing 160 pounds stands on the floor of an elevator what force will be exerted on the floor what if it descends with a uniform acceleration of 1 ft ft per second square and ascends with a uniform acceleration of 1 ft per second square
The primary coil of a transformer has 250 turns and which is surrounded by a flux of 5mWb. When the magnet moves, the flux reduced into 3mWb. If it is connected to a 220-V line, find the time interval during which the flux changes.
An 80kg painter stands on a uniform 25 kg platform board supported by two wooden poles on each side. If each of these two poles can only hold 1000N and they are located at the ends of the 4m platform, will it be safe for him to stand at 1m from one end of the platform?
An iceberg is submerged partially in the sea and remaining 1/3 part is outside the sea level. Use Archimedes' principle to determine the density of an iceberg.
If the piston in the hydraulic lift has a cross-sectional area of 0.10m^2, what air pressure must be produced by the compressor to support 20, 000N, the combined weight of car and lift?
1 (a) 1kg of water at a temperature of 20◦C is placed in contact with a cold reservoir held at a constant temperature of 4◦C. (i) What is the change in the internal energy of the water as it cools to 4◦C ? (The specific heat capacity of water is 4148 J K−1 kg−1 .) [1] (ii) Calculate the change in entropy of the water as it cools to 4◦C. [2] (iii)Calculate the change in entropy of the cold reservoir. [2] (iv) Is this process of cooling the water reversible or irreversible? Explain your answer. [1]
v) Assume now that rather than being placed in a direct contact with the cold reservoir the water is cooled from 20◦C to 4◦C by using the water as the heat source for a reversible heat engine. The cold reservoir still has a fixed temperature of 4◦C. How much work can be extracted from this heat engine? [6]
I need help with part (v) only, just including the above parts for context
