Answer:

Explanation:
given,
Angular speed of the tire = 32 rad/s
Displacement of the wheel = 3.5 rev
Δ θ = 3.5 x 2 π
= 7 π rad
now,
Time interval of the car to rotate 7π rad
using equation



Time taken to rotate 3.5 times is equal to 0.687 s.
The Doppler effect is the right concept to solve this problem. The Doppler effect is understood as the change in apparent frequency of a wave produced by the relative movement of the source with respect to its observer. Mathematically it can be described as,

Here,
= Frequency of the sound from the Whistle
f = Frequency of sound heard
v = Speed of the sound in the Air
Replacing we have that





Therefore the minimum speed to know if the whistle is working is 16.33m/s
Answer:

Explanation:
In this question we have given
mass of airplane=.6 Kg
Radius of horizontal circle,r=6m
Time taken to complete 1.6 revolution=5s
Therefore time taken to complete 1 revolution, t=
t=3.1 s
We have to find the speed of airplane
We will first find the distance covered by airplane in tracing one circle which is equal to circumference of circle
We know that
Circumference,d = 
or 

We know that speed=
............(1)
Put value of d and t in equation 1
speed=

6: Short way: it cannot be 2.5, 3, or 5 because up to 5 seconds it only has positive velocity so it must be moving forwards.
Long Way: Velocity is in m / s, multiply that by time (s) to get m or displacement. From 0->5 you have a triangle under the curve, (1/2)(5)(20) = 50 meters displaced positive, you need to then look when velocity is under the curve and use a similar equation to solve for the area but make the answer negative. Find the point where it equals -50 and that is where it will have returned.
Answer to 6: B
7. I cannot see the problem enough to answer this. Just know if the line is above 0 velocity is positive so it is moving the direction it started, when it goes below 0 velocity is negative so it is moving opposite direction it started.
8. Accelration is change in velocity. Whatever the slope of the velocity graph is acceleration. At t=8 the slope is 0 because it is not going up or down.
Answer to 8: A
Answer:
The magnification would be "103.55". A further explanation is given below.
Explanation:
The given values are:
Distance between lens and eyepiece,
L = 85 cm
Eyepiece is,
= 123 D
Now,
The refractive power of eye piece will be:
⇒ 


The length of the telescope will be:
⇒ 
⇒ 
On substituting the values, we get
⇒ 
⇒ 
Now,
The magnification of the telescope will be:
⇒ 
⇒ 
⇒ 