Answer:
1.98s
Explanation:
The time taken to hit the ground is given by
h=ut+ 1/2 at^2
but u =0
so we have
h=1/2at^2
making t the subject
t=√2h/g
√2×19.6/10
1.98s
Answer:
The capacitance of the capacitor is 
Explanation:
To solve this exercise it is necessary to apply the concepts related to Power and energy stored in a capacitor.
By definition we know that power is represented as

Where,
E= Energy
t = time
Solving to find the Energy we have,

Our values are:


Then,


With the energy found we can know calculate the Capacitance in a capacitor through the energy for capacitor equation, that is

Solving for C=



Therefore the capacitance of the capacitor is 
Answer:
<em>The speed of metal block B is 5 m/s after the collision</em>
Explanation:
<u>Law Of Conservation Of Linear Momentum
</u>
The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and velocity v is
P=mv.
If we have a system of bodies, then the total momentum is the sum of them all

If some collision occurs, the velocities change to v' and the final momentum is:

In a system of two masses, we have:

The metal block A has a mass of m1=3.2 Kg and moves at v1=4 m/s. Metal block b has a mass of m2=1.6 Kg and is initially at rest v2=0.
After the collision occurs, block A moves at v1'=1.5 m/s. We need to calculate the speed of the metal block B. Solving for v2':

Substituting the given values:



The speed of metal block B is 5 m/s after the collision
I think the answer is Black. Hope this helps