#21
- initial velocity=u=5m/s
- Time=t=2s
- Acceleration=a=1.3m/s²
According to first equation of kinematics
- v=u+at
- v=5+1.3(2)
- v=5+2.6
- v=7.6m/s
#22
#a
- v1=2+3(3)=2+9=11m/s
- v2=-8-4(3)=-20m/s
- v3=1-5(3)=-14m/s
The order is
#b
for speed find absolute velocity
- S1=|11|=11m/s
- S2=|-20|=20m/s
- S3=|-14|=14m/s
So order is
S1<S3<S2
Cosmology physics is used to describe the interaction of matter and energy from the beginning of the cosmic singularity to the Planck time.
Astronomy's field of cosmology examines the beginnings and development of the universe, from the Big Bang through the present and into the future. The current cosmology model for the development of the universe is the Big Bang theory, which relies on the validity of general relativity. There is a singularity there as well.
According to the Big Bang theory, the cosmos was once compressed into an infinitely small point 13.77 billion years ago. Prior to 
seconds after the Big Bang, during the Planck Era, gravity, nuclear strong, nuclear weak, and electromagnetic forces are thought to have been merged into a single "super" force.
Learn more about big bang theory here;
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16. Solids cannot transport heat through convection. Because solids are stuck in place so they can't flow and since they can't flow, there is no convection.
17. It is because the metal conducts heat faster that it feels colder than the wood, which conducted heat slower. In other words metals are good conductors of heat. It takes away your body heat as you touch it and which makes your body temperature to drop, therefore you feel the coldness when you touch a piece of metal.
Answer:
Time - taken = 2.5 s
deceleration= -8 m/s²
Solution:
Given:
speed, v = 8 m/s
distance, d = 20m
To Find:
deacceleration = ?
As we know speed is defined as
v = d/t
plugging in the values
t = 20/ 8
t = 2.5s
Now from deceleration formula
a = - v/ t
a = - 20/ 2.5
a = - 8 m/s²
Thus, the time taken and acceleration is 2.5 s and -8 m/s²
respectively.
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