Mars is the planet that's closest in size to Earth.
Answer:
Acceleration of the object is
.
Explanation:
It is given that, the position of the object is given by :
![r=[2\ m+(5\ m/s)t]i+[3\ m-(2\ m/s^2)t^2]j](https://tex.z-dn.net/?f=r%3D%5B2%5C%20m%2B%285%5C%20m%2Fs%29t%5Di%2B%5B3%5C%20m-%282%5C%20m%2Fs%5E2%29t%5E2%5Dj)
Velocity of the object, 
Acceleration of the object is given by :

![a=\dfrac{d^2}{dt^2}([2\ m+(5\ m/s)t]i+[3\ m-(2\ m/s^2)t^2]j)](https://tex.z-dn.net/?f=a%3D%5Cdfrac%7Bd%5E2%7D%7Bdt%5E2%7D%28%5B2%5C%20m%2B%285%5C%20m%2Fs%29t%5Di%2B%5B3%5C%20m-%282%5C%20m%2Fs%5E2%29t%5E2%5Dj%29)
Using the property of differentiation, we get :

So, the magnitude of the acceleration of the object at time t = 2.00 s is
. Hence, this is the required solution.
Answer:
9 cm.
Explanation:
The energy used for stretch the spring from
to
will be ,
The energy used for stretch the spring from
to
will be ,
using the energy of spring formula ,we find that


Dividing both the equation will get,

Therefore, the natural length of the spring is, 9 cm.