an object is thrown straight up. which of the following is true abought the sign of workdone by the force of gravity on the obje
1 answer:
Answer:
Upward: Negative
Downward: Positve
Explanation:
Let upward be positive
We want to find the work done on the object upwards.
The equation of work done due to gravity is
It is read as force of gravity times displacement times cos of the angle between the force and displacement.
Since gravity is happening down of the center of mass and the displacement is upwards, the angle is 180° so
Cosine of 180 is -1
so
If we go downwards, the sign will be positive because cos(0)=1
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Answer:
B. 0.16 m
Explanation:
The vertical distance by which the player will miss the target is equal to the vertical distance covered by the dart during its motion.
Since the dart is thrown horizontally, the initial vertical velocity is zero:
While the horizontal velocity is
The horizontal distance covered is
Since the dart moves by uniform motion along the horizontal direction, the time it takes for covering this distance is
along the vertical direction, the motion is a uniformly accelerated motion with constant downward acceleration g=9.8 m/s^2, so the vertical distance covered is given by