Physics Questions coming soon

g = 9.8ms^-2

1. A 5.4kg object, is in equilibrium, on a desk.

a) What is the weight of the object?

b) What is the mass of the object?

c) What is the magnitude of the force of the desk acting on the object?

d) What direction does the force of the desk act on the object?

2. Train A is 100m ahead of train B and travelling at 5ms^-1. Train B is travelling at 9ms^-1 and is decelerating at 1.1ms^-2. Find the values of the s and t.

3 significant figures.

s = 9t+ 1/2 X 1.1 X t^2

s = 5t + 100

s =_____m

t =_____s

I don`t know how to do these. Can u teach me as soon as possible?

1 個解答

評分
  • 天同
    Lv 7
    1 十年前
    最愛解答

    (a) weight of block = 5.4g N = 52.92 N

    (b) Mass = 5.4 kg

    (c) Force acting on the block = weight of block = 52.92 N

    (d) Pointing verticallly upward.

    2. What do s and t represent ? They are not mentioned in the question.

    s = 9t+ 1/2 X 1.1 X t^2 <-- this equation is wrong.

    When you apply the equation of motion to train B, a -ve sign should be given to a decceleration. The correct equation is:

    s = 9t + (1/2).(-1.1).t^2

    After you have got the correct equations, just solve the equations algebrically.

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