Answer: A 100-lb child stands on a scale while riding in an elevator. Then, the scale reading approaches to 100lb, while the elevator slows to stop at the lowest floor
Explanation: To find the correct answer, we need to know more about the apparent weight of a body in a lift.
<h3>What is the apparent weight of a body in a lift?</h3>
- Consider a body of mass m kept on a weighing machine in a lift.
- The readings on the machine is the force exerted by the body on the machine(action), which is equal to the force exerted by the machine on the body(reaction).
- The reaction we get as the weight recorded by the machine, and it is called the apparent weight.
<h3>How to solve the question?</h3>
- Here we have given with the actual weight of the body as 100lbs.
- This 100lb child is standing on the scale or the weighing machine, when it is riding .
- During this condition, the acceleration of the lift is towards downward, and thus, a force of ma .
- There is also<em> mg </em>downwards and a normal reaction in the upward direction.
- when we equate both the upward force and downward force, we get,
i.e. during riding the scale reads a weight less than that of actual weight.
- When the lift goes slow and stops the lowest floor, then the acceleration will be approaches to zero.
Thus, from the above explanation, it is clear that ,when the elevator moves to the lowest floor slowly and stops, then the apparent weight will become the actual weight.
Learn more about the apparent weight of the body in a lift here:
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Answer:
a)The gravitational force would be twice as much as it is now
Explanation:
If the earth had twice its mass as it is now, the gravitational force between the sun and the earth would be twice as much as it is now.
According to Newton's law of universal gravitation "the gravitational force of attraction between bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them".
F =
G is the universal gravitation constant
m is the mass
r is the distance
let mass of sun = s
mass of earth = e
new mass of sun = s
new mass of sun = 2e
input variables;
F = ------ i
F = ------- ii
From the second equation;
2F =
2F = F
Therefore, the force will double.
Translation of question
A ship is used to measure the depth of the sea using sound devices. A sound was fired at the bottom of the water and five seconds later there was a bounce. If the speed of sound in the water is 1500 m / s, then the depth of the water is
Answer:
3750 m
Explanation:
For sound to bounch back and be heard, this phenomenon is echo. Therefore, the distance traveled is 2d. Considering that speed is distance per unit time, expressed as s=d/t where d is distance, t is time and s is speed, in this case we say s=2d/t. Making d the subject of the formula then d=0.5st
Given 5 s as time and 1500 m/s as speed, we deduce that d=0.5*1500*5=3750 m
Answer:
79.98
if this is a simple math problem, the (•) signifies multiplication
The speed of sound in a solid would be 6000 metres per second