<span>here's a cheap trick
it would take the same time to accelerate from rest to top speed
as it would take to decelerate from top speed to zero
so
instead of
d = Vi t + 1/2 a t^2 where Vi is positive and a is negative
we'll use
Vi = 0 and a is positive
giving
85 = 0 + 1/2 (0.43) t^2 = 0.215 t^2
t^2 = 395.345
t = 19.88s or 20. s to 2 sig figs
or we ccould find Vi from
Vf*2 = Vi^2 + 2 a d
0 = Vi^2 + 2 (0.43) 85
Vi^2 = 71.4
Vi = 8.45m/s
then
85 = 8.45 t + 1/2 (-0.43) t^2
85 = 8.45 t - 0.215 t^2
0.215 t^2 - 8.45 + 85 = 0
t = 19.65s or 20. s to 2 s.f.(minor difference arises from rounding Vi)
or another cheap trick
when a is constant
Vavg = (Vf + Vi) /2 = 8.45/2 = 4.225
and
d = Vavg t
85 = 4.225 t
t = 20.12 or 20. s to 2 s.f. (minor differences from intermidiate roundings)
anyway you choose you get 20. s</span>
Answer:
I think that this ans may help you
Answer:
Stretching vibration and bending vibration
Explanation:
1. Stretching vibration results in the variation of the bond length. There are two types of stretching vibration:
- In asymmetric bending, bonds move in and out as a result of the vibration.
- In symmetric bending, bonds move such that the bond length either gets shorter or longer.
2. Bending vibration results in the variation of the bond angle.
These can be grouped into 4 types:
- Rocking- It is that motion in which two atoms are in the motion like that of the motion of a pendulum of a clock.
- Scissoring- The motion of to atoms either away from each other or towards each other.
- Twisting- It is where the motion of the two atoms resembles that of the motion on a treadmill.
- Wagging- It is the motion in V- shape in the back and forth direction.
Answer:
Weight, W = 400 N
Explanation:
Give that,
Mass of a girl, m = 40 kg
We need to find the weight of a girl.
Weight of an object is given by :
W = mg
g is the acceleration due to gravity
Putting all the values,
W = 40 kg × 10 m/s²
= 400 N
Hence, the weight of a girl is 400 N.
When it comes to optics, the most basic equation to use is the Snell's Law:
n₁ sin θ₁ = n₂ sin θ₂
where θ₁ is the angle of incidence, θ₂ is the angle of refraction, and n are the index of refractions depending on the type of medium.
This equation is used when light strikes from one medium to another and you want to determine the angle of refraction. For example, as light travels from air to water, the light bends as it strike the water. The observable change you can see is that things tend to look bigger when viewed from afar.
In this case, the first medium is air which has an index of refraction of 1. So, n₁ = 1. Then, n₂ is for the glass which is equal to 25°. Substituting the values,
(1) sin 25° = (1.5) sin θ₂
θ₂ = 16.36°