If <em>A</em> = <em>i</em> - <em>j</em> + <em>k</em>, then the magnitude of <em>A</em> is
||<em>A</em>|| = √(1² + (-1)² + 1²) = √3
Then the unit vector in the direction of <em>A</em> is 1/||A|| multiplied by <em>A</em> :
<em>u</em> = <em>A</em>/||<em>A</em>|| = (<em>i</em> - <em>j</em> + <em>k</em>)/√3
(choice D)
The average kinetic energy of the atoms that make up a substance which is changing from a liquid to a solid is <span>decreasing. The answer is letter A. This is because there is more room for movement of atoms if the pahse is in liquid than in solid.</span>
Answer:
132 N
Explanation:
Given that a 1.1 kg hammer strikes a nail. Before the impact, the hammer is moving at 4.5 m/s; after the impact it is moving at 1.5 m/s in the opposite direction. If the hammer is in contact with the nail for 0.025 s, what is the magnitude of the average force exerted by the hammer on the nail
From Newton 2nd law of motion,
Change in momentum = impulse.
Change in momentum = m( V - U )
Substitute all the parameters into the formula
Change in momentum = 1.1 ( 4.5 - 1.5 )
Change in momentum = 1.1 × 3
Change in momentum = 3.3 kgm/s
Impulse = Ft
That is,
Ft = 3.3
Substitute time t into the formula above
F × 0.025 = 3.3
F = 3.3 / 0.025
F = 132 N
Therefore, the magnitude of the average force exerted by the hammer on the nail is 132 N.
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