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IRINA_888
6 days ago
14

You testify as an expert witness in a case involving an accident in which car A slid into the rear of car B, which was stopped a

t a red light along a road headed down a hill (Fig. 6-25). You find that the slope of the hill is u " 12.03, that the cars were separated by distance d " 24.0 m when the driver of car A put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car A at the onset of braking was v0 " 18.0 m/s.With what speed did car A hit car B if the coefficient of kinetic friction was (a) 0.60 (dry road surface) and (b) 0.10 (road surface covered with wet leaves)
Physics
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A merry-go-round with a a radius of R = 1.63 m and moment of inertia I = 196 kg-m2 is spinning with an initial angular speed of
serg [3582]

Answer:

1) L = 299.88 kg-m²/s

2) L = 613.2 kg-m²/s

3) L = 499.758 kg-m²/s

4) ω₁ = 0.769 rad/s

5) Fc = 70.3686 N

6) v = 1.2535 m/s

7) ω₀ = 1.53 rad/s

Explanation:

Given

R = 1.63 m

I₀ = 196 kg-m²

ω₀ = 1.53 rad/s

m = 73 kg

v = 4.2 m/s

1) What is the magnitude of the initial angular momentum of the merry-go-round?

We utilize the formula

L = I₀*ω₀ = 196 kg-m²*1.53 rad/s = 299.88 kg-m²/s

2) What is the angular momentum magnitude of the person 2 meters prior to jumping onto the merry-go-round?

The equation we apply is

L = m*v*Rp = 73 kg*4.2 m/s*2.00 m = 613.2 kg-m²/s

3) What is the angular momentum of the person just before she hops onto the merry-go-round?

We utilize the formula

L = m*v*R = 73 kg*4.2 m/s*1.63 m = 499.758 kg-m²/s

4) What is the angular velocity of the merry-go-round after the individual jumps on?

We can apply the Principle of Conservation of Angular Momentum

L in = L fin

⇒ I₀*ω₀ = I₁*ω₁

where

I₁ = I₀ + m*R²

⇒  I₀*ω₀ = (I₀ + m*R²)*ω₁

At this point, we can determine ω₁

⇒  ω₁ = I₀*ω₀ / (I₀ + m*R²)

⇒  ω₁ = 196 kg-m²*1.53 rad/s / (196 kg-m² + 73 kg*(1.63 m)²)

⇒  ω₁ = 0.769 rad/s

5) Once the merry-go-round moves at this new angular speed, what force must the person exert to hold on?

We must calculate the centripetal force as follows

Fc = m*ω²*R  

⇒  Fc = 73 kg*(0.769 rad/s)²*1.63 m = 70.3686 N

6) When the person is halfway around, they choose to simply release their hold on the merry-go-round to exit the ride.

What is the linear speed of the person the moment they exit the merry-go-round?

we can apply the equation

v = ω₁*R = 0.769 rad/s*1.63 m = 1.2535 m/s

7) What is the angular velocity of the merry-go-round after the individual releases their hold?

ω₀ = 1.53 rad/s

It returns to its original angular speed

8 0
1 month ago
As Aubrey watches this merry-go-round for a total of 2 minutes, she notices the black horse pass by 15 times. What is the period
Sav [3153]
2 minutes = 120 seconds

120/15 = 8

The black horse corresponds to 8 seconds.
8 0
1 month ago
Read 2 more answers
A 5 kg block moves with a constant speed of 10 ms to the right on a smooth surface where frictional forces are considered to be
Yuliya22 [3333]

Answer:

The work done, W = 19.6 J

Explanation:

It’s provided that

The mass of the block, m = 5 kg

The velocity of the block, v = 10 m/s

The coefficient of kinetic friction between the block and rough surface is 0.2

Distance traveled by the block, d = 2 m

As the block traverses the rough section, it loses energy equal to the work done by the kinetic energy.

W=\mu_kmgd

W=0.2\times 5\times 9.8\times 2

W = 19.6 J

Thus, the change in kinetic energy of the block moving through the rough section is 19.6 J. Consequently, this is the required answer.

5 0
2 months ago
Read 2 more answers
A 2.1 × 103 kg car starts from rest at the top of a driveway that is sloped at an angle of 20.0° with the horizontal. An average
Keith_Richards [3271]

Answer:

The driveway measures 4.98 m

Explanation:

We aim to find the length of the driveway, thus utilizing the following equations

W=ΔK.E    where W represents work and  ΔK.E   indicates the change in kinetic energy

Moreover,

K.E = \frac{ MV^2}{2}also

W = F.d  where F is the force and d denotes distance

Given that

= 4000 N indicating this frictional force

F_{f} m = 2100 Kg  

θ= 20.0°  

V=3.8 m/s representing the car's speed at the bottom of the driveway

W=Δ K.E

=  15162  J  

W = (1/2)(2100)(3.8)^2As the x component of gravity is

= mg sinФ

Fx_thus

= (2100)(9.8)sin(20.0°) results in

Fx_{} = 7038.77 N

And the Net force isFx_{}

=

-

F_{net}Fx_ {} = 7038.77 - 4000 = 3038.77 NF_{f}

So, the length of the driveway equals W / (

) = 15162/3038.77 = 4.98 m F_{net}

F_{net}

Thus, this is the length of the driveway.

3 0
1 month ago
Which statements describe properties of stars check all that apply
Keith_Richards [3271]

Answer:

Stars generate energy by the process of nuclear fusion.

They are large entities composed of gaseous elements.

The main constituents of stars are hydrogen and helium.

Explanation:

Stars are colossal objects with extensive gravitational forces causing them to contract, which allows fusion to take place: the atomic nuclei in the star's core are drawn very close together due to gravity and elevated temperatures, leading to the fusion reaction. This fusion serves as the energy output for a star.

Conversely, it is true that stars predominantly consist of hydrogen and helium (two hydrogen nuclei can fuse to become helium), which implies that a star is essentially an enormous ball of gas without a solid surface suitable for standing on.

As for the presence of water on a star, it is simply impossible. The extreme temperatures found in stars are far too high for water to exist in any liquid state on their surfaces.

7 0
2 months ago
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