Answer:
A
Explanation:
- The complete question is:
" A crate is lifted vertically 1.5 m and then held at rest. The crate has weight 100 N (i.e., it is supported by an upward force of 100 N).Now suppose the crate is lifted so rapidly that air resistance was significant during the raising. How much work was done by the lifting force as the box was raised 1.5 m?"
Options:
1. More than 150 J
2. A bit less than 150 J because the air partially supported the crate.
3. No work was done.
4. Still 150 J
5. None of these
Solution:
- As the box is raised the work is done against gravity and air resistance opposes the motion of box. Hence, both the force of gravity ( Weight and air resistance act downward).
- The amount of work done is the sum of both work done against gravity and against air resistance.
- W = W_g + W_r
W > W_g
W > 100*1.5
W > 150 J
- Hence, the work done is greater than 150 J i.e work is also done against ai r resistance.
Answer:
0.1962N.
Explanation:
Weight is a force, so we use newtons second law which states F=ma. So the weight of a watermelon on earth is 2kg x 9.81m/s², which is 19.62N (newtons). On the moon it weighs 2 x 1.63 which is 3.26N.
The weight of the pen is 0.02 x 9.81, which is 0.1962N. If the pen is not to fall the frictional force needs to be equal to this force,
so the answer is 0.1962N.
(Hope this helps can I pls have brainlist (crown)☺️)
Answer:
options A and C
Explanation:
Since, the spheres are of same size and rotational speed of the sphere are not dependent on their masses. So, both the sphere will reach the bottom of the at the same time with the same speed. But their kinetic energies are different.
So, options A and C are correct.
Answer:
D. infinitely extended in all directions
Explanation:
A semi infinite solid is infinitely extended in every direction. It has a single surface and can extend when heat is applied.
The body of a semi infinite solid is idealised, that is, when there is heat present, it expands in all directions to infinity. It can be used for a thick wall because its shape can be changed when subjected to different levels of heat near its surface.
It is also expands as heat is applied because its thickness is negligible.
This idealized body is used for earth, thick wall, steel piece of any shaped quenched rapidly etc indetermining variation of temperature near its surface & other surface being too far to have any impact on the region in short period of time since heat doesn’t have sufficient time to penetrate deep into body thus thickness can be neglected
We have that the Number of stitches per sec and he mass of oscillation motion is mathematically given as
a) Nt=25stitches per sec
b) m=2.033e-5kg
<h3>
Number of
stitches per sec and he mass of oscillation motion</h3>
Question Parameters:
This <u>sewing </u>machine is capable of stitching 1,500 stiches in one minute.
If the <em>sewing </em>machine has a spring constant of 0.5 N/m,
Generally the equation for the Number of stitches per sec is mathematically given as
Nt=N/t
Therefore
Nt=1500/60
Nt=25stitches per sec
b)
Generally the equation for the Time t is mathematically given as
Therefore
m=2.033e-5kg
For more information on Mass visit
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