# Posts by LYNA

• ## Chapter 2

LYNA

PT02 Fornalha

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Mechanical comprehension test:

Q1: Which wire is carrying the most weight? B

1. A
2. B
3. No difference
4. Depends on the time of day

Q2: Which object will not float on water? Scissors

1. Empty plastic bottle
2. Wooden pencil
3. Banana
4. Scissors

Q3: Which way will the boat go through the water? A

1. A
2. B
3. It will continue moving unchanged
4. It will slow down but without changing direction

Q4: At which position will the moving pendulum travel the fastest? B

1. A
2. B
3. C
4. No difference

Q5: Where is the temperature change highest throughout the day? A

1. A
2. B
3. Where both meet
4. No difference

Q6: If cog A turns clockwise by 20 rotations, how will cog B turn? 10 rotations anticlockwise

1. 20 rotations anticlockwise
2. 20 rotations clockwise
3. 10 rotations anticlockwise
4. 10 rotations clockwise

Q7: To balance the bar, how much weight should be positioned on the left side? 2.5 kg

1. 25 kg
2. 10 kg
3. 5 kg
4. 2.5 kg

Q8: If block B is moved to the right by 20 cm,

by how many centimetres will block A move upwards? 20 cm

1. 5 cm
2. 10 cm
3. 20÷3 cm
4. 20 cm

Q9: A block slides down an inclined plane with an acceleration of A.

If the mass of the block is doubled, how will this affect its acceleration? 0.5 x A

1. Acceleration will still be A
2. 2 x A
3. 0.5 x A

Q10: If the right plunger is moved down by 5 cm,

how much will the left plunger move up? Less than 5 cm

1. Exactly 5 cm
2. Less than 5 cm
3. More than 5 cm
4. It won't move
• ## Chapter 1

Problem:

Due to a technical error, two trains were accidently assigned to the same rail track and are now approaching each other. The communication system of both trains is broken and the conductors don't know about the imminent danger they're in.

By the time a supervisor at one of the offices notices the problem, the trains are only 140 km away from each other. The speed of train A is 160 km/h; the speed of train B is 120 km/h.

There's a manual switch that could stop both trains from colliding, but the supervisor is 6,300 metres away from it and he needs to get there first. If he runs at an average speed of 14 km/h, will he be in time to save the trains?

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### Correct explanation:

1 -The speed of train A is 160 km/h = 160.000 m/h = 2 667 metres / minute

2 -The speed of train B is 120 km/h = 120.000 m/h = 2 000 metres / minute

3 -They are 140 km away from each other and will be in touch in 30 minutes:

Train A - 30 min x 2 667 m = 80 000 mt = 80 Km

Train B - 30 min x 2 000 m = 60 000 mt = 60 Km

80 Km + 60 Km = 140 Km in 30 minutes

4 - The supervisor is 6,300 metres away, at an average speed of 14 km/h:

14 Km/h = 14 000 m/h = 233 metres / minute

6,300 / 233 = 27 minutes

The supervisor arrived early less 3 minutes than the pervasively trains contact.

LYNA