Answer:
(4) 8.5 m/s
Explanation:
You add both the meters together and both the seconds together and then divide them both.
Answer : The correct option is, (c) 
Explanation :
First we have to calculate the energy or heat.
Formula used :

where,
E = energy (in joules)
V = voltage (in volt)
I = current (in ampere)
t = time (in seconds)
Now put all the given values in the above formula, we get:


Now we have to calculate the heat capacity of the calorimeter.
Formula used :

where,
C = heat capacity of the calorimeter
= initial temperature = 
= final temperature = 
Now put all the given values in this formula, we get:


Therefore, the heat capacity of the calorimeter is, 
Answer:
v = 19.6 m/s
Explanation:
Height of building = 30.6 m.
Height of window from the ground level= 10.7 m.
Acceleration due to gravity = 9.8 
At initial condition ball at rest condition so u= 0 m/s.
Lets take when passes through the window ,velocity is v.
Here acceleration is constant so we can apply motion equation .
We know that
v= u + a t
So by putting the values
v = 0 +9.8 x 2
v = 19.6 m/s
So the velocity of ball is 19.6 m/s when passes through the window after 2 s.