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Lesson Worksheet: Newton’s Third Law of Motion Mathematics
In this worksheet, we will practice solving problems on Newton’s third law.
Q6:
A body of mass 75 kg was attached to a string fixed to the ceiling of an elevator. Starting from rest, the elevator began accelerating vertically upward at 44 cm/s2. During this time the tension in the string was . After accelerating, the elevator continued moving at the speed it had gained, at which point the tension in the string was . Finally, the elevator decelerated at 24 cm/s2, at which point the tension in the string was . Determine the magnitudes of , , and . Consider the acceleration due to gravity to be 9.8 m/s2.
- A, ,
- B, ,
- C, ,
- D, ,
Q9:
A man was standing on a set of scales in an elevator, recording the readings as the elevator moved. His first reading was when the elevator was accelerating upward at a rate of . He made another reading when the elevator was accelerating downward at a rate of . Given that the ratio between the two readings was , determine where is the acceleration due to gravity.
- A
- B
- C
- D
Q10:
A body of mass 686 g was suspended to a spring balance fixed to the ceiling of a lift. When the lift started moving, the reading on the balance was 672 g. Determine whether the lift was ascending or descending, and find the speed , 5 seconds after it started moving. Consider the acceleration due to gravity .
- Aascending,
- Bascending,
- Cdescending,
- Ddescending,