C is the first & the second question is A
Answer:
x(t) = - 6 cos 2t
Explanation:
Force of spring = - kx
k= spring constant
x= distance traveled by compressing
But force = mass × acceleration
==> Force = m × d²x/dt²
===> md²x/dt² = -kx
==> md²x/dt² + kx=0 ------------------------(1)
Now Again, by Hook's law
Force = -kx
==> 960=-k × 400
==> -k =960 /4 =240 N/m
ignoring -ve sign k= 240 N/m
Put given data in eq (1)
We get
60d²x/dt² + 240x=0
==> d²x/dt² + 4x=0
General solution for this differential eq is;
x(t) = A cos 2t + B sin 2t ------------------------(2)
Now initially
position of mass spring
at time = 0 sec
x (0) = 0 m
initial velocity v= = dx/dt= 6m/s
from (2) we have;
dx/dt= -2Asin 2t +2B cost 2t = v(t) --- (3)
put t =0 and dx/dt = v(0) = -6 we get;
-2A sin 2(0)+2Bcos(0) =-6
==> 2B = -6
B= -3
Putting B = 3 in eq (2) and ignoring first term (because it is not possible to find value of A with given initial conditions) - we get
x(t) = - 6 cos 2t
==>
Answer:
Height = 53.361 m
Explanation:
There are two balloons being thrown down, one with initial speed (u1) = 0 and the other with initial speed (u2) = 43.12
From the given information we make the following summary
= 0m/s
= t
= 43.12m/s
= (t-2.2)s
The distance by the first balloon is
where
a = 9.8m/s2
Inputting the values
The distance traveled by the second balloon
Inputting the values
simplifying
Substituting D of the first balloon into the D of the second balloon and solving
Now we know the value of t. We input this into the equation of the first balloon the to get height of the apartment
Answer:
200 N
Explanation:
Given that,
A ball traveling at 15 m/s hits a bat with a force of 200 N.
We need to find the force that the bat moving at 20 m/s hit the ball with.
We know that, this probelm is based on Newton's third law of motion. The force that the ball exerting on bat should be equal to the force that the bat exerting in the ball but in opposite direction.
It would mean that the ball hits the ball with a force of 200 N. Hence, the correct option is (a).
