31 (unit)
acceleration formula
net force (124)
Acceleration = -------------
mass (4)
124÷4=31
Answer:
The family in the first period is the alkali metal family.
Answer:
Kinetic energy is maximum when the player hits the ball.
Explanation:
Kinetic energy 
, where m is the mass and v is the velocity.
So kinetic energy is proportional to square of velocity.
Velocity is maximum when the player hits the ball.
So kinetic energy is maximum when the player hits the ball.
Q3. (a) 0m/s, as they are asking for initial velocit.
(b)(i) The paper has a large surface area or weighs less than the coin,thus,falls smoothly.
(ii)The coin has more mass than the paper.
(c) They fall at the same acceleration and hit the bottom at the same time.
Their mass doesn't matter in the vacuum.
