Answer:
20 mins
Explanation:
To go 90 km it takes =60 mins(1 hr)
" " 1 km it takes =60/90 mins
" " 30 km it takes =60/90 multiplied by 30
= 20 mins
Answer:
average acceleration is 1.365 ×
m/s²
Explanation:
given data
initila speed u = -32.2 m/s
final speed v = 21.6 m/s
time taken t = 0.00394 s
solution
we get here average acceleration that will be express as
v = u + at ..........................1
put here value and we get
21.6 = -32.2 + a × 0.00394
solve it we get
a = 1.365 ×
m/s²
so average acceleration is 1.365 ×
m/s²
Question: How fast was the arrow moving before it joined the block?
Answer:
The arrow was moving at 15.9 m/s.
Explanation:
The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:

where
is the mass of the arrow,
is the mass of the block,
of the change in height of the block after the collision, and
is the velocity of the arrow before it hit the block.
Solving for the velocity
, we get:

and we put in the numerical values
,



and simplify to get:

The arrow was moving at 15.9 m/s
Coal, petroleum, and natural gas are considered nonrenewable because they can not be replenished in a short period of time
4 water has a low heat capacity and a high vaporization temperate and coasts have low temps