Answer:
20 J
Explanation:
Kinetic energy is given as half of the product of mass and the square of velocity of an object:
KE =
where m = mass = 40 kg
v = velocity = 1 m/s
Hence, Mary's kinetic energy is:
KE =
KE = 20 * 1 = 20 J
She has a kinetic energy of 20 J.
Units of impulse: N • s, kg • meters per second
Explanation:
Impulse is defined in two ways:
1)
Impulse is defined as the product between the force exerted in a collision and the duration of the collision:
where
F is the force
is the time interval
Since the force is measured in Newtons (N) and the time is measured in seconds (s), the units for the impulse are
So,
N • s
2)
Impulse is also defined as the change in momentum experienced by an object:
where the change in momentum is given by
where m is the mass and is the change in velocity.
The mass is measured in kilograms (kg) while the change in velocity is measured in metres per second (m/s), therefore the units for impulse are
so,
kg • meters per second
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