Answer:
v= 300 m/s
Explanation:
Given that
altitude ,h= 4500 m
The mass ,m = 3 kg
Lets take acceleration due to gravity , g= 10 m/s²
The speed before impact at sea level = v
Initial speed ,u = 0 m/s
We know that
v²=u²+2 g h
v=final speed
u=initial speed
h=height
Now by putting the values in the above equation
v² = 0²+ 2 x 10 x 4500
v²=90000
v= 300 m/s
Therefore the speed at sea level will be 300 m/s.
Answer:D: the velocity is zero
Explanation:
Answer:
-39.2m/s
Explanation:
Given that :
t = 4secs
g = -9.8m/s^2
v = ?
u = 0m/s ( since it was at rest )
V = u +at............. 1
Where v is the final velocity
a = -g = -9.8m/s^2 since the ball was dropped from a height which will eventually make it move against gravity
t = 4secs
Substitute the values into 1
v = 0 - 9.8×4
v = -39.2m/s
The qualifications boil down to: College education.
In most university or industrial research organizations, you might be able to work there as a member of the team who doesn't get much pay or much respect, with research going on all around you directed by other people, after you've gotten you Master's degree.
But you really don't have a shot at leading anything, or having much to say about what's being researched or how, until you have a PhD degree in the field where you'd like to do the research.
(Did I mention how proud I was to be present about 6 weeks ago, in a land far away, when my daughter was awarded a PhD degree in Molecular Biology ? I didn't want to let you get away without hearing about that.)
Answer:
a) Acceleration is zero
, c) Speed is cero
Explanation:
a) the equation that governs the simple harmonic motion is
x = A cos (wt +φφ)
Where A is the amplitude of the movement, w is the angular velocity and φ the initial phase determined by the initial condition
Body acceleration is
a = d²x / dt²
Let's look for the derivatives
dx / dt = - A w sin (wt + φ)
a = d²x / dt² = - A w² cos (wt + φ)
In the instant when it is not stretched x = 0
As the spring is released at maximum elongation, φ = 0
0 = A cos wt
Cos wt = 0 wt = π / 2
Acceleration is valid for this angle
a = -A w² cos π/2 = 0
Acceleration is zero
b)
c) When the spring is compressed x = A
Speed is
v = dx / dt
v = - A w sin wt
We look for time
A = A cos wt
cos wt = 1 wt = 0, π
For this time the speedy vouchers
v = -A w sin 0 = 0
Speed is cero
