Answer:

Explanation:
The motion of the skater is a uniformly accelerated motion, so we can find the deceleration by using the following suvat equation:

where
v is the final velocity
u is the initial velocity
a is the acceleration
s is the displacement
In this problem, we have:
u = 19 m/s is the initial velocity of the skater
v = 18 m/s is the final velocity of the skater
s = 2.0 m is the displacement
Solving for a, we can find the acceleration:

And the negative sign tells us that the acceleration is in the opposite direction to the motion (so, it is a deceleration)

As galáxias são geralmente maiores do que os aglomerados de estrelas. Como disse Geller ~ As galáxias são como as cidades em que vivem os aglomerados de estrelas. As galáxias podem ter cerca de milhares ou mais aglomerados de estrelas ~
I hope it helps ~
M = mass of the ball A = 5.0 kg
m = mass of the ball B = ?
V = initial velocity of the ball A before collision = 20 m/s
v = initial velocity of the ball B before collision = 10 m/s
V' = final velocity of the ball A after collision = 10 m/s
v' = final velocity of the ball B after collision = 15 m/s
using conservation of momentum
M V + m v = M V' + m v'
(5.0) (20) + m (10) = (5.0) (10) + m (15)
100 + 10 m= 50 + 15 m
5 m = 50
m= 10 m/s