V₀ = V₁ + 2ax
V₀ = final velocity which is 0 m/s
V₁ = initial velocity which is 20 m/s
x = distance which is 60-(0.5 x 20) =50m
this is because his reaction time is 0.5 sec so he traveled 10m before stepping on the break paddle.
a= (V₀-V₁) / 2x
= (0-20) / 2*50
= -0.2m/s
the negative is because it is a deceleration speed hence it is 0.2m/s
Answer:

Explanation:
Let the radius of the hemisphere is R. The mass is released from rest so the initial speed is equal to zero and acceleration is equal to the g.
By the Newton's 3rd equation,
Now, at the bottom hemisphere the centripetal acceleration will act on the mass and the direction of this force is towards center,

Hence, the acceleration on the bottom of the hemisphere is equal to the 2g.
Probably gas because it will reach Nobel gas state
<span>The medium in which it travels through</span>
The speed of sound at sea level is 340.29 m/s (meters per seconds).