Answer:
His acceleration is 
Explanation:
Newton's second law states that acceleration of a body is cause by a net force, the relation between them is:
On the boy there're acting two forces, his weight (W) that points downward and the frictional force (f) that points upward (they boy moves downward and friction always is opposite to movement). So 
so (1) is:
Using the positive direction downward weight and gravitational acceleration(g) are positive and friction force is negative:
, solving for a:
, weight is mg:
The launch proyectiles of kinematics allows to find the maximum initial vertical velocity of the body so that it just reaches the ceiling
v_{oy} = 2.56 m / s
Given parameters
- The ceiling height y = 3 m
To find
Projectile launching is an application of kinematics where on the x axis there is no acceleration or and on the y axis the acceleration is the acceleration of gravity (g = 9.8 m / s ^ 2)
In this case, the maximum vertical velocity that the body can have occurs when the velocity on the ceiling is zero.
v_y² = v_{oy}² - 2 g y
where v and v_{oy} are the initial velocity at the ceiling e initial, respectively, g the acceleration of gravity e and the height
0 = v_{oy}² - 2 g y
v_{oy} = 
v_{oy} = 
v_{oy} = 2.56 m / s
In conclusion with the kinematic of launch projectiles we can find the maximum initial vertical velocity of the body so that it just reaches the ceiling
v_{oy} = 2.56 m / s
learn more about projectile launch here:
brainly.com/question/10903823
Answer:
It takes you 32.27 seconds to travel 121 m using the speed ramp
Explanation:
<em>Lets explain how to solve the problem</em>
- The speed ramp has a length of 121 m and is moving at a speed of
2.2 m/s relative to the ground
- That means the speed of the ramp is 2.2 m/s
- You can cover the same distance in 78 seconds when walking on
the ground
<em>Lets find your speed on the ground</em>
Speed = Distance ÷ Time
The distance is 121 meters
The time is 78 seconds
Your speed on the ground = 121 ÷ 78 = 1.55 m/s
If you walk at the same rate with respect to the speed ramp that
you walk on the ground
That means you walk with speed 1.55 m/s and the ramp moves by
speed 2.2 m/s
So your speed using the ramp = 2.2 + 1.55 = 3.75 m/s
Now we want to find the time you will take to travel 121 meters using
the speed ramp
Time = Distance ÷ speed
Distance = 121 meters
Speed 3.75 m/s
Time = 121 ÷ 3.75 = 32.27 seconds
It takes you 32.27 seconds to travel 121 m using the speed ramp
Say the initial point is (0,0)
The final point is
x = 200 + 135*cos(30) = 200 + 135*sqrt(3)/2 = 316.91 ft
y = 135*sin(30) = 135/2 = 67.5 ft
Resultant vector = (316.91, 67.5) - (0,0) = 316.91, 67.5) ft
Force (N) = mass (kg) x velocity (m/s) / time (s)
