Answer:

Explanation:
To solve this problem we use the Momentum's conservation Law, before and after the girl catch the ball:
(1)
At the beginning the girl is stationary:
(2)
If the girl catch the ball, both have the same speed:
(3)
We replace (2) and (3) in (1):

We can now solve the equation for v_{f}:

If a coin is dropped at a relatively low altitude, it's acceleration remains constant. However, if the coin is dropped at a very high altitude, air resistance will have a significant effect. The initial acceleration of the coin will be the greatest. As it falls down, air resistance will counteract the weight of the coin. So, the acceleration will decrease. Although the acceleration decreases, the coin still accelerates, that is why it falls faster. When the air resistance fully counters the weight of the coin, the acceleration will become zero and the coin will fall at a constant speed (terminal velocity). So, the answer should be, The acceleration decreases until it reaches 0. The closest answer is.
a. The acceleration decreases.
Answer:
Net electric field, 
Explanation:
Given that,
Charge 1, 
Charge 2, 
distance, d = 3.2 cm = 0.032 m
Electric field due to charge 1 is given by :



Electric field due to charge 2 is given by :



The point charges have opposite charge. So, the net electric field is given by the sum of electric field due to both charges as :



So, the electric field strength at the midpoint between the two charges is 91406.24 N/C. Hence, this is the required solution.
Answer:d
Explanation:
Spring is compressed to a distance of x from its equilibrium position
Work done by block on the spring is equal to change in elastic potential energy
i.e. Work done by block 
therefore spring will also done an equal opposite amount of work on the block in the absence of external force
Thus work done by spring on the block 
Thus option d is correct