When an object moves its length contracts in the direction of motion. The faster it moves the shorter it gets in the direction of motion.
The object in this question moves and then stops moving. So it's length first contracts and then expands to its original length when the motion stops.
The speed doesn't have to be anywhere near the speed of light. When the object moves its length contracts no matter how fast or slow it's moving.
We have centripetal acceleration = 
So, v = 
Now by equation of motion we have S= ut +0.5a
S =displacement, u = initial velocity, a= acceleration and t = time
Here S = 2r and a = g , u = 0
Distance traveled in horizontal direction = 
Answer
given,
number of dog = 8
mass of each dog= 19 Kg
mass of sled = 210 Kg
average force = 185 Nss
a) writing all the horizontal force
force acting by dog - friction force = (M + 8m) a
8 F_d - μ m g = (M + 8m) a
assuming coefficient of friction of snow be μ = 0.14
8 x 185 - 0.14 x 210 x 9.8 = (210 + 8 x 19 ) x a
a = 3.29 m/s²
b) the kinetic friction of coefficient is less than static friction
hence, we can suggest that acceleration of the sled will increase once the sled start to move.
a > 3.29 m/s²
A 60.0 kg secretary running up a 4.0 m tall flight of stairs in 4.2 s has an average power of 560 W (Option b).
<h3>What is power?</h3>
Power is the work done over a period of time.
A secretary with a mass (m) of 60.0 kg runs up a 4.0 m (d) tall flight of stairs. Given gravity (g) is 9.81 m/s², the work (W) done is:
W = m × g × d = 60.0 kg × 9.81 m/s² × 4.0 m = 2.35 × 10³ J
They do 2.4 × 10³ J of work in 4.2 s (t). The average power (P) is:
P = W / t = 2.35 × 10³ J / 4.2 s = 560 W
A 60.0 kg secretary running up a 4.0 m tall flight of stairs in 4.2 s has an average power of 560 W (Option b).
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The final velocity of object 2 is: 3 m/sec
<h3>What is the conservation of mass?</h3>
According to the rule of conservation of mass, no atoms are created or destroyed during a chemical process. Instead, the atoms combine in a variety of ways to create goods. This explains why each element has the equal amount of atoms on both sides of an equation with balanced symbols.
According to conservation of mass,
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Given that,
m₁ = 50 kg
m₂ = 75 kg
u₁ = 4 m/s
u₂ = -1 m/s
v₁ = -2 m/s
v₂ = ?
Now, putting the values,
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
(50 × 4) + [75 × (-1)] = [50 × (-2)] + (75 × v₂)
or, 125 = -100 + 75 v₂
or, 75 v₂ = 225
or, v₂ = 3 m/sec.
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