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madreJ [45]
2 years ago
14

The suspension cable of a 1,000 kg elevator snaps, sending the elevator moving downward through its shaft. The emergency brakes

of the elevator stop the elevator shortly before it reaches the bottom of the shaft. If the elevator fell a distance of 100 m starting from rest, the heat that the brakes must dissipate to bring the elevator safely to rest is (A) 100 J (B) 1,000 J (C) 10,000 J (D) 100,000 J (E) 1,000,000 J
Physics
1 answer:
tester [92]2 years ago
4 0

Answer:

option (E) 1,000,000 J

Explanation:

Given:

Mass of the suspension cable, m = 1,000 kg

Distance, h = 100 m

Now,

from the work energy theorem

Work done by the gravity = Work done by brake

or

mgh = Work done by brake

where, g is the acceleration due to the gravity = 10 m/s²

or

Work done by brake  = 1000 × 10 × 100

or

Work done by brake = 1,000,000 J

this work done is the release of heat in the brakes

Hence, the correct answer is option (E) 1,000,000 J

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Wood block 1 in (Figure 1), which has a mass of 1.0 kg, is at rest on a wood ramp. The angle of the ramp is 20º above horizontal
Sergeeva-Olga [200]

Answer:

Explanation:

For this problem we use the translational equilibrium condition. Our reference frame for block 1 is one axis parallel to the plane and the other perpendicular to the plane.

X axis

      -Aₓ - f_e +T = 0        (1)

Y axis

      N₁ - W_y = 0              ( 2)

let's use trigonometry for the weight components

      sin θ = Wₓ / W

      cos θ = W_y / W

      Wₓ = W sin θ

      W_y = W cos θ

We write the diagram for the second body.

Note that in the block the positive direction rd upwards, therefore for block 2 the positive direction must be downwards

      W₂ -T = 0                             (3)

we add the equations is 1 and 3

       - W₁ sin θ - μ N₁ + W₂ = 0

from equation 2

       N₁ = W₁ cos θ

       

we substitute

        -W₁ sin θ - μ (W₁ cos θ) + W₂ = 0

W₂ = m₁ g (without ea - very expensive)

This is the smallest value that supports the equilibrium system

7 0
2 years ago
A cyclist goes around a circular track once every 2 minutes. If the radius of the circular track is 105 meters calculate his spe
Bad White [126]
The formula should be (2πr)/T. r=radius T=time. if time is in seconds the formula would look like this
\frac{2\pi \times 105}{60 \times 2}
8 0
2 years ago
Read 2 more answers
Rank, from largest to smallest, the following four collisions according to the magnitude of the change in the momentum of cart B
sertanlavr [38]

Answer:

The largest to smallest change in momentum with respect to magnitude of change in momentum is as follows;

1st- Collision (1) & Collision (2 or b in question)

2nd- Collision (4)

3rd- Collision (3)

Explanation:

This is because momentum is mass times into velocity. i.e.

P=m.v (kg.m/s - S.I unit)

(where p is momentum, m is mass of object and v is velocity or speed object)

If mass remains constant(real life scenario) then change in momentum is directly related to change in speed. i.e

Δp=m⋅(Δv)=m⋅(vf−vi) where vf is final velocity and vi is initial velocity.

By using above formula ;

we can calculate change in momentum for different collisions with respect to cart B.

m= mass of cart B

Collision (1) Δp=m⋅(Δv)=m⋅(vf−vi)=m.(0-1.0)=-m kg.m/s (where "-" indicates deceleration or stopping of object.)

Collision (2 or b in question ) Δp=m⋅(Δv)=m⋅(vf−vi)=m.(0-1.0)=-m kg.m/s

Collision (3) Δp=m⋅(Δv)=m⋅(vf−vi)=m.(0-0)=0 (which indicates that object remains stationary before and after collision and momentum for cart B is 0)

Collision (4) Δp=m⋅(Δv)=m⋅(vf−vi)=m.(0.67-0)=0.67m kg.m/s

Therefore collisions (1) and (2 or b) are ranked 1st, collision (4) ranked 2nd and collision (3) ranked 3rd.

4 0
2 years ago
A pesticide was applied to a population of roaches, and it was determined that the LD50 was 55mgkg. If the average mass of a roa
zhannawk [14.2K]

Answer:

55mg/kg * 0.02kg which gives 1.1 mg pesticides

Explanation:

(Options are missing)

If the average mass or weight of a roach is 0.02kg

And 55mg is needed per 1 kg roaches

The amount or size of pesticide required for 0.02kg roach is 55mg/kg * 0.02kg

Size = 55mg/kg * 0.02 kg

Size = 1.1mgkg/kg

Size = 1.1 mg

So, the size of pesticide required is 1.1mg

0 0
2 years ago
A 0.56 kg model rocket produces 53 newtons of upward thrust as it shoots upward off the launch pad. With what acceleration meter
Yanka [14]

resultant force = thrust – weight

acceleration = resultant force (newtons, N) divided by mass (kilograms, kg).

Acceleration = resultant force divided by mass

53N/0.56

=94.64 approximately 95

= 95m/s^2

This means that, every second, the speed of the rocket increases by 95m/s2

the S.I unit of Acceleration is meter per second square.

6 0
1 year ago
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