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harkovskaia [24]
3 years ago
10

Two trains traveling towards one another on a straight track are 300m apart when the engineers on both trains become aware of th

e impending Collision and hit their brakes. The eastbound train, initially moving at 97.0 km/h Slows down at 3.50ms^2. The westbound train, initially moving at 127 km/h slows down at 4.20 m/s^2. What is the distance between them once they stop (express your answer to the two significant figures)
Physics
1 answer:
sattari [20]3 years ago
5 0

Answer:

48 m

Explanation:

Two trains traveling towards one another on a straight track are 300m apart when the engineers on both trains become aware of the impending Collision and hit their brakes. The eastbound train, initially moving at 97.0 km/h Slows down at 3.50ms^2. The westbound train, initially moving at 127 km/h slows down at 4.20 m/s^2.

The eastbound train

First convert km/h to m/s

(97 × 1000)/3600

97000/3600

26.944444 m/s

As the train is decelerating, final velocity V = 0 and acceleration a will be negative. Using third equation of motion

V^2 = U^2 - 2as

O = 26.944^2 - 2 × 3.5 S

726 = 7S

S = 726/7

S1 = 103.7 m

The westbound train

Convert km/h to m/s

(127×1000)/3600

127000/3600

35.2778 m/s

Using third equation of motion

V^2 = U^2 - 2as

0 = 35.2778^2 - 2 × 4.2 × S

1244.52 = 8.4S

S = 1244.52/8.4

S2 = 148.2 m

S1 + S2 = 103.7 + 148.2 = 251.86

The distance between them once they stop will be

300 - 251.86 = 48.14 m

Therefore, the distance between them once they stop is 48 metres approximately.

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Which object has the most gravitational potential energy?
Kipish [7]

Answer: An 8 kg book at a height of 3 m has the most gravitational potential energy.

Explanation:

Gravitational potential energy is the product of mass of object, height of object and gravitational field.

So, formula to calculate gravitational potential energy is as follows.

U = mgh

where,

m = mass of object

g = gravitational field = 9.81 m/s^{2}

h = height of object

(A) m = 5 kg and h = 2m

Therefore, its gravitational potential energy is calculated as follows.

U = mgh\\= 5 kg \times 9.81 m/s^{2} \times 2 m\\= 98.1 J    (1 J = kg m^{2}/s^{2})

(B) m = 8 kg and h = 2 m

Therefore, its gravitational potential energy is calculated as follows.

U = mgh\\= 8 kg \times 9.81 m/s^{2} \times 2 m\\= 156.96 J    (1 J = kg m^{2}/s^{2})

(C) m = 8 kg and h = 3 m

Therefore, its gravitational potential energy is calculated as follows.

U = mgh\\= 8 kg \times 9.81 m/s^{2} \times 3 m\\= 235.44 J    (1 J = kg m^{2}/s^{2})

(D) m = 5 kg and h = 3 m

Therefore, its gravitational potential energy is calculated as follows.

U = mgh\\= 5 kg \times 9.81 m/s^{2} \times 3 m\\= 147.15 J    (1 J = kg m^{2}/s^{2})

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3 0
3 years ago
Please help!!!!!!!!!​
Elena-2011 [213]

Answer:

v = 12.86 km/h

v = 3.6 m/s

Explanation:

Given,

The distance, d = 13.5 km

The time, t = 21/20 h

                  =  1.05 h

The velocity of a body is defined as the distance traveled by the time taken.

                                     v = d / t

                                        =  13.5 km / 1.05 h

                                        = 12.86 km/h

The conversion of km/h to m/s

                                   1 km/h = 0.28 m/s

                                     12.86 km/h = 12.86 x 0.28 m/s

                                                         = 3.6 m/s

Hence, the velocity in m/s is, v = 3.6 m/s

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