My guess is A. I'm not 100% positive but i'm pretty sure.
Answer:
Explanation:
1) acceleration is the change in velocity of a body with respect to time.
acceleration = velocity/time
Given
velocity = 139m/s
time = 20secs
acceleration = 139/20
acceleration = 6.95m/s²
Hence its average acceleration during the first 20 seconds of the launch is 6.95m/s²
2) Speed is the rate of change of distance with respect to time.
average speed = distance/time
Time = distance/speed
Time = 100/7823
Time = 0.013s
3) Using the equation of motion v² = u²+2as
v² = 0²+2(15)(60)
v² = 30*60
v² =1800
v = √1800
v = 42.43m/s
Answer:
gexp = 3.65 m/s²
Explanation:
The value of acceleration due to gravity changes with the altitude. The following formula gives the value of acceleration due to gravity at some altitude from the sea level:
gexp = g(1 - 2h/Re)
where,
gexp = expected value of g at altitude = ?
g = acceleration due to gravity at sea level = 9.8 m/s²
h = altitude = 2000 km = 2 x 10⁶ m
Re = Radius of Earth = 6.37 x 10⁶ m
Therefore,
gexp = (9.8 m/s²)(1 - 2*2 x 10⁶ m/6.37 x 10⁶ m)
<u>gexp = 3.65 m/s²</u>
Because chemical changes result in different substances, they often cannot be undone. Some chemical changes can be reversed, but only by other chemical changes.