Question

A kid throws a pencil straight up at

Answer 1

Answer:

Explanation:

The boy throw the pencil upward at a speed of 6.33 m/s

Then,

Initial velocity of throw is 6.33 m/s

u = 6.33 m/s.

Time to reach a maximum height of 1.25m

h = 1.25m

Note: at maximum height, the final velocity is zero

v = 0m/s

Acceleration due to gravity is

g = 9.81m/s²

We want to calculate time to reach maximum height

t = ?

Then, applying equation of motion

v = u + gt

But since it is against gravity, then, g is negaive

Then,

v = u - gt

0 = 6.33 - 9.81t

-6.33 = -9.81t

Then,

t = -6.33 / -9.81

t = 0.645 seconds

Answer 2

Answer:

The time you use the pencil to reach the ceiling is 0.6459 s

Explanation:

Given:

v = speed = 6.33 m/s

h = high = 1.25 m

g = gravity = 9.8 m/s²

Question: How much time does it take for the pencil to reach the ceiling, t = ?

The equation for calculate the time is:

$v_{y} =v_{initial} +gt$

In this case vinitial = 0, since the pencil comes out of his hand. Solving for t:

$t=\frac{v_{y} }{g} =\frac{6.33}{9.8} =0.6459s$