Answer:
c) The distance between the balls increases.
Explanation:
If you drop the balls at the same time, regardless of their masses they accelerate equally, since they will be in free fall.
However, if you drop one of the balls earlier, then that ball will gain velocity, whereas the second ball has zero initial velocity. At the time the second ball is dropped, both balls have the same acceleration but different initial velocities.
According to the below kinematics equation:

The initial velocity of the first ball will make the difference, and the first ball will travel a greater distance than the second ball. Hence, their distance increases.
If it's a mechanical wave, then its speed depends on the physical characteristics of the medium.
If it's an electromagnetic wave, then its speed depends on the
electrical characteristics of the medium.
Either way, the properties of the medium determine the wave speed.
You want to change the speed ? You have to change the properties
of the medium.
One scientist proposes an idea and other scientists repeat his or her experiments so they can Accept the Idea.
Answer: The correct option is (c.).
Explanation:
Mass of the cart A= 1.5 kg
Velocity of Cart A = 1.4 m/s towards right
Mass of the cart B = 1.0 kg
Velocity of Cart B = 1.4 m/s towards left
Momentum (P)= Mass × Velocity

(Negative sign means velocity of the cart is in opposite direction of that of the cart A)
Total Momentum =
Hence, the correct option is (c.).
Answer: 0.5 m/s
Explanation:
Given
Speed of the sled, v = 0.55 m/s
Total mass, m = 96.5 kg
Mass of the rock, m1 = 0.3 kg
Speed of the rock, v1 = 17.5 m/s
To solve this, we would use the law of conservation of momentum
Momentum before throwing the rock: m*V = 96.5 kg * 0.550 m/s = 53.08 Ns
When the man throws the rock forward
rock:
m1 = 0.300 kg
V1 = 17.5 m/s, in the same direction of the sled with the man
m2 = 96.5 kg - 0.300 kg = 96.2 kg
v2 = ?
Law of conservation of momentum states that the momentum is equal before and after the throw.
momentum before throw = momentum after throw
53.08 = 0.300 * 17.5 + 96.2 * v2
53.08 = 5.25 + 96.2 * v2
v2 = [53.08 - 5.25 ] / 96.2
v2 = 47.83 / 96.2
v2 = 0.497 ~= 0.50 m/s