A. the medium through which the light travels changes.
Explanation:
Light waves will continue to travel in a straight line in all directions from their source unless the medium through which the light travels changes.
A change in medium causes light to exhibit different properties. Also, when light hits an obstacle, they can be diffracted.
- The way light travels on crossing a boundary differs.
- At the boundary between two medium, light can either be reflected back or refracted when they cross the medium
- This will cause the light rays to bend towards or away from the normal depending on the properties of the medium.
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Answer:
9 meters
Explanation:
Given:
Mass of Avi is, 
Spring constant is, 
Compression in the spring is, 
Let the maximum height reached be 'h' m.
Now, as the spring is compressed, there is elastic potential energy stored in the spring. This elastic potential energy is transferred to Avi in the form of gravitational potential energy.
So, by law of conservation of energy, decrease in elastic potential energy is equal to increase in gravitational potential energy.
Decrease in elastic potential energy is given as:

Now, increase in gravitational potential energy is given as:

Now, increase in gravitational potential energy is equal decrease in elastic potential energy. Therefore,

Therefore, Avi will reach a maximum height of 9 meters.
Answer:
t_total = 23.757 s
Explanation:
This is a kinematics exercise.
Let's start by calculating the distance and has to reach the limit speed of
v = 18.8 m / s
v = v₀ + a t₁
the elevator starts with zero speed
v = a t₁
t₁ = v / a
t₁ = 18.8 / 2.40
t₁ = 7.833 s
in this time he runs
y₁ = v₀ t₁ + ½ a t₁²
y₁ = ½ a t₁²
y₁ = ½ 2.40 7.833²
y₁ = 73.627 m
This is the time and distance traveled until reaching the maximum speed, which will be constant throughout the rest of the trip.
x_total = x₁ + x₂
x₂ = x_total - x₁
x₂ = 373 - 73,627
x₂ = 299.373 m
this distance travels at constant speed,
v = x₂ / t₂
t₂ = x₂ / v
t₂ = 299.373 / 18.8
t₂ = 15.92 s
therefore the total travel time is
t_total = t₁ + t₂
t_total = 7.833 + 15.92
t_total = 23.757 s
As we know that total work done by a force is given by


so it is product of force and displacement along same direction
as we can write it as

so it must be the product of force and displacement in same directions so correct answer must be
<u>B. in the same direction as the displacement vector and the motion.</u>
Answer:
Explanation:
Given that:
the initial angular velocity 
angular acceleration
= 4.44 rad/s²
Using the formula:

Making t the subject of the formula:

where;

∴

t = 0.345 s
b)
Using the formula:

here;
= angular displacement
∴



Recall that:
2π rad = 1 revolution
Then;
0.264 rad = (x) revolution

x = 0.042 revolutions
c)
Here; force = 270 N
radius = 1.20 m
The torque = F * r

However;
From the moment of inertia;

given that;
I = 84.4 kg.m²

For re-tardation; 
Using the equation



t = 0.398s
The required time it takes= 0.398s