A parachutist of mass 100 kg falls from a height of 500 m. Under realistic conditions, she experiences air resistance. Based on
what you know about friction, what can you say about the kinetic energy of the parachutist as she reaches the ground? Remember, 1 kJ = 1000 J. Acceleration due to gravity is g = 9.8 m/s2.
2 answers:
Answer:
Explanation:
It is given that,
Mass of the parachutist, m = 100 kg
It falls from a height of 500 meters.
When the parachutist reaches the ground, the potential energy gets converted to its kinetic energy. The potential energy of the parachutist is given by the following formula as :
g is the acceleration due to gravity
Since, 1 kJ = 1000 J
So,
So, as the parachutist reaches ground its kinetic energy is equal to 490 kJ.
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Answer:
The gravitational force changing velocity is
Explanation:
The expression for the gravitational force is
Differentiate the above equation
The velocity is the distance in at time so
Answer:
1) 883 kgm2
2) 532 kgm2
3) 2.99 rad/s
4) 944 J
5) 6.87 m/s2
6) 1.8 rad/s
Explanation:
1)Suppose the spinning platform disk is solid with a uniform distributed mass. Then its moments of inertia is:
If we treat the person as a point mass, then the total moment of inertia of the system about the center of the disk when the person stands on the rim of the disk:
2) Similarly, he total moment of inertia of the system about the center of the disk when the person stands at the final location 2/3 of the way toward the center of the disk (1/3 of the radius from the center):
3) Since there's no external force, we can apply the law of momentum conservation to calculate the angular velocity at R/3 from the center:
4)Kinetic energy before:
Kinetic energy after:
So the change in kinetic energy is: 2374 - 1430 = 944 J
5)
6) If the person now walks back to the rim of the disk, then his final angular speed would be back to the original, which is 1.8 rad/s due to conservation of angular momentum.