Answer:
Approximately
.
Explanation:
The formula for the kinetic energy
of an object is:
,
where
is the mass of that object, and
is the speed of that object.
Important: Joule (
) is the standard unit for energy. The formula for
requires two inputs: mass and speed. The standard unit of mass is
while the standard unit for speed is
. If both inputs are in standard units, then the output (kinetic energy) will also be in the standard unit (that is: joules,
Convert the unit of the arrow's mass to standard unit:
.
Initial
of this arrow:
.
That's the same as the energy output of this bow. Hence, the efficiency of energy transfer will be:
.
Answer:
0.405 seconds
Explanation:
Consider the amount of time it takes the block to fall from 53 m up to 14 m above the ground; then consider the amount of time it takes the block to fall from 53 m up to 2 m above the ground.
First, d = (1/2) gt^2 or t= ( 2 d / g)^1/2
= ( 2 × 39 / 9.8)^1/2 = 2.8212 seconds
Then, to fall from 53 down to 2 meters...
d = (1/2) gt^2 or t= ( 2 d / g)^1/2
= ( 2 * 51/ 9.8 )^1/2 = 3.2262 seconds
So the amount of time it takes for the block to fall from 14 m upto 2 m above the ground
3.2262 - 2.8212 = 0.405 seconds
this is how much time there is from when the man sees the block until it hits him. Not much time...
Answer:
Approximately
to the right (assuming that both astronauts were originally stationary.)
Explanation:
If an object of mass
is moving at a velocity of
, the momentum
of that object would be
.
Since momentum of this system (of the astronauts) conserved:
.
Assuming that both astronauts were originally stationary. The total initial momentum of the two astronauts would be
since the velocity of both astronauts was
.
Therefore:
.
The final momentum of the first astronaut (
,
to the left) would be
to the left.
Let
denote the momentum of the astronaut in question. The total final momentum of the two astronauts, combined, would be
.
.
Hence,
. In other words, the final momentum of the astronaut in question is the opposite of that of the first astronaut. Since momentum is a vector quantity, the momentum of the two astronauts magnitude (
) but opposite in direction (to the right versus to the left.)
Rearrange the equation
to obtain an expression for velocity in terms of momentum and mass:
.
.
Hence, the velocity of the astronaut in question (
) would be
to the right.
Well...they came from a single bacteria and self produce them...if they grew.there will be millions of them...