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27. A 28. C It depends on the object's mass and the acceleration due to gravity, which is 9.8 m/s2 on Earth. The formula for calculating weight is F = m × 9.8 m/s2, where F is the object's weight in Newtons (N) and m is the object's mass in kilograms. The Newton is the SI unit for weight, and 1 Newton equals 0.225 pounds.
29. D 2 m s − 2
Explanation: Simply use the formula F = m a
From this the acceleration is obtained by a = F m
Thus a = 40 20 = 2 m s − 2
30. A If the net force acting on an object doubles, its acceleration is doubled. If the mass is doubled, then acceleration will be halved. If both the net force and the mass are doubled, the acceleration will be unchanged.
Answers & Comments
28. C
It depends on the object's mass and the acceleration due to gravity, which is 9.8 m/s2 on Earth. The formula for calculating weight is F = m × 9.8 m/s2, where F is the object's weight in Newtons (N) and m is the object's mass in kilograms. The Newton is the SI unit for weight, and 1 Newton equals 0.225 pounds.
29. D
2
m
s
−
2
Explanation:
Simply use the formula
F
=
m
a
From this the acceleration is obtained by
a
=
F
m
Thus
a
=
40
20
=
2
m
s
−
2
30. A
If the net force acting on an object doubles, its acceleration is doubled. If the mass is doubled, then acceleration will be halved. If both the net force and the mass are doubled, the acceleration will be unchanged.