Weight is a force that depends on mass and: *
2 answers:
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Answer:
The Kinetic Energy INCREASE in the following situations:
a)A block slides down a frictionless incline:
e)A merry go round rotates faster due to the push by a person.
Explanation:
The energy kinetics is proportional to the square of the velocity:
We study the cases:
a)A block slides down a frictionless incline:
The gravity made a positive work and the box get a extra velocity, then the kinetics energy INCREASE
b)A box is pulled across a rough floor at constant speed:
The magnitude of the velocity does not change, so the kinetics energy does not change as well
c)A stone at the end of a string is whirled in a horizontal circle at constant speed:
The magnitude of the velocity does not change, so the kinetics energy does not change as well
d)A projectile approaches its maximum height:
If the projectile approaches its maximum height, its velocity approaches to zero. Then the kinetics Energy DECREASE
e)A merry go round rotates faster due to the push by a person.
Thanks to the push, the magnitude of the velocity INCREASE, so the kinetics energy INCREASE as well
Answer:
0.001 s
Explanation:
The force applied on an object is equal to the rate of change of momentum of the object:
where
F is the force applied
is the change in momentum
is the time interval
The change in momentum can be written as
where
m is the mass
v is the final velocity
u is the initial velocity
So the original equation can be written as
In this problem:
m = 5 kg is the mass of the fist
u = 9 m/s is the initial velocity
v = 0 is the final velocity
F = -45,000 N is the force applied (negative because its direction is opposite to the motion)
Therefore, we can re-arrange the equation to solve for the time: