Answer:
(a) Time t = 16.46 sec
(b) Time t =13.466 sec
(c) Deceleration = 
Explanation:
(a) As the train starts from rest its initial velocity u = 0 m/sec
Acceleration 
Final speed v = 80 km/hr
From first equation of motion v =u+at
So 
(b) Now initial speed u = 22.22 m/sec
As finally train comes to rest so final speed v=0 m/sec
Deceleration 
So 
(c) We have given that initial velocity = 80 km/hr = 22.22 m/sec
Final velocity v = 0 m/sec
Time t = 8.30 sec
So acceleration is given by
As acceleration is negative so it is a deceleration
True
In fact, the weight of an object on the surface of the Earth is given by:
where m is the mass of the object and
is the gravitational acceleration on Earth's surface. If we use the mass of the object, m=3.0 kg, we find
Answer:
The mantle exists above the crust of the earth
Answer:
a) 
Now we can replace the velocity for t=1.75 s
For t = 3.0 s we have:
b) 
And we can find the positions for the two times required like this:
And now we can replace and we got:
Explanation:
The particle position is given by:
Part a
In order to find the velocity we need to take the first derivate for the position function like this:
Now we can replace the velocity for t=1.75 s
For t = 3.0 s we have:
Part b
For this case we can find the average velocity with the following formula:
And we can find the positions for the two times required like this:
And now we can replace and we got:
