A brick falls freely from a high scaffold.

A. What is its velocity after 4.0s?

B. How far does the brick fall during the first 4.0s?

I don't know what formula to use. I only have time, and I guess the first velocity would be 0s.

finalvelocity=initialvelocity + g*time

g= 9.8m/s^2

for how far, see your other post.

To solve these questions, we can use the equations of motion for an object in free fall.

The equation for velocity (v) of an object in free fall is given by v = gt, where g represents the acceleration due to gravity (approximately 9.8 m/s²) and t is the time.

The equation for the distance (s) covered by an object in free fall is given by s = 1/2 * gt².

A. To find the velocity after 4.0s, we can use the equation v = gt. Since the initial velocity is 0, we have:

v = g * t
v = 9.8 m/s² * 4.0s
v = 39.2 m/s

Therefore, the velocity of the brick after 4.0 seconds is 39.2 m/s.

B. To find the distance the brick falls during the first 4.0s, we can use the equation s = 1/2 * gt². Again, we substitute g = 9.8 m/s² and t = 4.0s into the equation:

s = 1/2 * 9.8 m/s² * (4.0s)²
s = 1/2 * 9.8 m/s² * 16.0s²
s = 78.4 m

Therefore, the brick falls a distance of 78.4 meters during the first 4.0 seconds.

To solve these problems, you can use the formulas of motion under constant acceleration, which is given by the equation:

v = u + at

where:
v = final velocity,
u = initial velocity,
a = acceleration, and
t = time.

In this case, the brick falls freely, meaning it is under the influence of gravity, which causes it to accelerate downward. The acceleration due to gravity is approximately 9.8 m/s².

A. What is its velocity after 4.0s?

Since the initial velocity of the brick is 0 m/s (as it starts from rest), you can use the equation:

v = u + at

v = 0 + (9.8 m/s²)(4.0s)
v = 0 + 39.2 m/s
v ≈ 39.2 m/s

Therefore, the velocity of the brick after 4.0 seconds is approximately 39.2 m/s.

B. How far does the brick fall during the first 4.0 seconds?

To determine the distance fallen, you can use the equation of motion:

s = ut + (1/2)at²

where:
s = distance fallen.

As the initial velocity is 0 m/s, the equation simplifies to:

s = (1/2)at²

s = (1/2)(9.8 m/s²)(4.0s)²
s ≈ (1/2)(9.8 m/s²)(16 s²)
s ≈ (1/2)(156.8 m)
s ≈ 78.4 m

Therefore, the brick falls approximately 78.4 meters during the first 4.0 seconds.