Plus and minus signs are used in one-dimensional motion to indicate direction. What is the sign of an acceleration that reduces the magnitude of a negative velocity? Of a positive velocity?
A. For negative velocity a positive acceleration will increase the magnitude of the velocity. For positive velocity a negative acceleration will reduce the magnitude of the velocity.
B. For negative velocity a positive acceleration will reduce the magnitude of the velocity. For positive velocity a negative acceleration will reduce the magnitude of the velocity.
C. For negative velocity a negative acceleration will reduce the magnitude of the velocity. For positive velocity a negative acceleration will reduce the magnitude of the velocity.
2. if an object is thrown straight up and air resistance is negligible, then (a) what will be its speed when it returns to the starting point on the ground? (b) If air resistance were not negligible, then how would the maximum height to which it rises be affected?
a) The final return accelerati0on on the ground will be the same as the initial value. (b) The minimum height will be lower.
b) The final return speed on the ground will not be the same as the initial speed. (b) The maximum height will be lower.
c) The final return speed on the ground will be the same as the initial speed. (b) The maximum height will be lower.
Answer: B. For negative velocity a positive acceleration will reduce the magnitude of the velocity. For positive velocity a negative acceleration will reduce the magnitude of the velocity.
2. Answer: c) The final return speed on the ground will be the same as the initial speed. (b) The maximum height will be lower.
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