Mechanics Chap.1-2

Which of the following matchings about the prefix of unit is correct?

• n 10^-8

• M 10³

• k 10^-2

• µ 10^-6

Peter and Mary take the same time to travel from H to K via P₁ to P₂ respectively. Which of the following statements about their journey is correct?

• The distances travelled by Peter and by Mary are the same.

• The average velocity of Peter is smaller than that of Mary.

• The displacements of Peter and Mary are the same.

Which of the following statements about the instantaneous velocity of an object is correct?

• Its direction is always the same as the direction of the average velocity.

• It shows how fast and the direction an object is moving at a certain instant.

• The instantaneous speed is greater than the magnitude of the instantaneous velocity.

An object moves along a straight line. Which of the following statements must be true?

• When the velocity is negative, it must be moving in the negative direction.

• When the acceleration is negative, it must be slowing down.

• When the acceleration is negative, it must be moving in the negative direction.

Which of the following graphs shows an object moving with a positive uniform velocity?

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Which of the following graphs shows an object moving with a uniform deceleration (slowing down)?

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Which of the graphs definitely shows that the object changes its moving direction?

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Tom and Paul start running at t = 0 at the same starting position. Which of the following statements is correct?

• Paul is decelerating in the period shown.

• Paul leads Tom at t = t₁.

• Paul and Tom meet each other at t = t₂.

The displacement-time graph of an object moving along a straight path is shown. Which of the following graphs best represents its velocity-time graph?

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