A briefcase sits stationary in an elevator. The mass of the briefcase if 4.5 kg. The elevator then begins accelerating upwards a
1 answer:
Answer:
D. 48.985 N
Explanation:
Newton's second law states that:
which means that the net force acting on an object is equal to the product between the object's mass and its acceleration.
The equation of the forces for the briefcase in the elevator therefore is given by:
where
N is the normal reaction exerted on the briefcase
(mg) is the weight of the briefcase, with
m = 4.5 kg being its mass
g = 9.8 m/s^2 is the acceleration of gravity
a = 1.10 m/s^2 is the acceleration
Here we chose upward as positive direction.
Solving for N, we find the normal force:
So the closest answer is
D. 48.985 N
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Answer:
Part-1: a)
Part-2: b)
Explanation:
Part-1
- Since Nice is pushed horizontally, in the vertical direction, he has no initial component of velocity, due to both movements are independent each other.
- Since the dock collapses, this means that in the vertical direction, the movement of Mean is exactly the same as Nice's.
- The expression for the vertical displacement is given by the following equation:
- So, due to the time of flight is determined by the height exclusively, and they start from the same height, we can conclude that they will hit the water at the same time.
- So, the right answer is the a) for Part-1.
Part-2
- The speed of both kids is given by the vector sum of the vertical and horizontal components of velocity when they hit the water.
- Mean falls vertically, with no component of velocity in the horizontal direction.
- In the vertical direction, Nice falls with exactly the same speed, as they hit water at the same time.
- However, Nice has a horizontal component of the velocity, that keeps constant during all his flight, as no external forces act in the horizontal direction.
- So, the magnitude of Nice's speed must be larger than Mead's, due to the vertical components are the same, and the extra horizontal component of Nice's adds to the vertical one.
- So, the right answer is b.) for Part-2.