The answer is D hope it helps
Answer:
Explanation:
Given
height of grand canyon is 
Rock is dropped i.e. initial velocity is zero

Using Equation of motion

h=height
u=initial velocity
a=acceleration
t=time
here a=acceleration due to gravity


Answer:
U² = 142.86 N
U¹ = 357.14 N
Explanation:
Taking summation of the moment about point A, we get the following equilibrium equation: (taking clockwise direction as positive)

where,
W = weight of boy = 500 N
U² = reaction ay B = ?
Therefore,

<u>U² = 142.86 N</u>
Now, taking summation of forces on the plank. Taking upward direction as positive, for equilibrium position:

<u>U¹ = 357.14 N</u>
Answer:
8.3m/s
Explanation:
Given parameters:
mass of clay ball = 5kg
Speed of clay ball = 25m/s
mass of clay ball at rest = 10kg
speed of clay ball at rest = 0m/s
Unknown:
Velocity after collision = ?
Solution:
Since the balls stick together, this is an inelastic collision:
m1v1 + m2v2 = v(m1 + m2)
5(25) + 10(0) = v (5 + 10)
125 = 15v
v = 8.3m/s