
- A ball is dropped from a height = H
- The total distance covered in last second of its motion is equal to the distance covered in first 3 second .

- The height of the journey .

We have know that,

Where,
- u = initial velocity = 0m/s
[Note :- Here, acceleration is ‛acceleration due to gravity’ .]
=> S = 1/2 × 10 × (3)^2
=> S = 5 × 9
=> S = <u>4</u><u>5</u><u>m</u> -----(1)
✒ If the ball takes ‛n’ second to fall the ground, then distance covered in nth second is,

=> Sn = 0 + 10/2 (2 × n - 1)
=> Sn = 5 (2n - 1)
=> Sn = 10n - 5 -----(2)
Therefore,
=> 10n = 45 + 5
=> n = 50/10
=> n = <u>5</u>
Now put the value of ‛n = 5’ in equation(2), we get
=> Sn = 10 × 5 - 5
=> Sn = 50 - 5
=> <u>Sn</u><u> </u><u>=</u><u> </u><u>4</u><u>5</u><u>m</u>
The height of the journey is “ <u>4</u><u>5</u><u>m</u> ” .
Explanation:
In physical sciences, mechanical energy is the sum of potential energy and kinetic energy. It is the macroscopic energy associated with a system. The principle of conservation of mechanical energy states that if an isolated system is subject only to conservative forces, then the mechanical energy is constant. If an object moves in the opposite direction of a conservative net force, the potential energy will increase; and if the speed (not the velocity) of the object changes, the kinetic energy of the object also changes. In all real systems, however, nonconservative forces, such as frictional forces, will be present, but if they are of negligible magnitude, the mechanical energy changes little and its conservation is a useful approximation. In elastic collisions, the kinetic energy is conserved, but in inelastic collisions some mechanical energy may be converted into thermal energy. The equivalence between lost mechanical energy (dissipation) and an increase in temperature was discovered by James Prescott Joule.
Answer:
work done lifting the bucket (sand and rope) to the top of the building,
W=67.46 Nm
Explanation:
in this question we have given
mass of bucket=20kg
mass of rope=
height of building= 15 meter
We have to find the work done lifting the bucket (sand and rope) to the building =work done in lifting the rope + work done in lifting the sand
work done in lifting the rope is given as,
=
..............(1)
=
=22.5 Nm
work done in lifting the sand is given as,
.................(2)
Here,
F=mx+c
here,
c=20-18
c=2
m=
m=.133
Therefore,

Put value of F in equation 2


Therefore,
work done lifting the bucket (sand and rope) to the top of the building,
W=22.5 Nm+44.96 Nm
W=67.46 Nm
Answer: Scattering reflection
Sunlight reaches earth's atmosphere and is scattered in all directions by all the gasses and particles in the air. Blue light is seen more than others because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.
Explanation: