4. Brick A is hurled vertically upward from a bridge at an initial speed of 4.90 m/s. One second later, Brick B is thrown horizontally from the same bridge with an initial speed of 9.80 m/s. Which hits the water first?

To determine which brick hits the water first, we need to calculate the time it takes for each brick to reach the water.

Let's start with Brick A, which is thrown vertically upward. We can use the kinematic equation for vertical motion:

v = u + at

where:
v is the final velocity (which is 0 m/s when the brick hits the water),
u is the initial velocity (4.90 m/s),
a is the acceleration due to gravity (-9.8 m/s²), and
t is the time.

Rearranging the equation, we have:

t = (v - u) / a

Plugging in the known values:

t_A = (0 - 4.90) / -9.8
t_A = 0.50 seconds

Now let's calculate the time it takes for Brick B to hit the water. Since Brick B is thrown horizontally, its vertical velocity is always 0 m/s. We only need to consider the horizontal motion.

Since Brick B has an initial horizontal velocity of 9.80 m/s and the vertical motion is not relevant, we can ignore gravity for this calculation.

t_B = Horizontal distance / Horizontal velocity
t_B = 0 / 9.80
t_B = 0 seconds

From the calculations, we can see that Brick B hits the water first, in 0 seconds, while Brick A takes 0.50 seconds to hit the water.

Therefore, Brick B hits the water before Brick A.