These answers are wrong, but I don\'t know which ones? Can anyone help me. Isn\'

Question

These answers are wrong, but I don't know which ones? Can anyone help me. Isn't acceleration always the same and the velocity is zero at the top.  

Points Q and R are at the same height and S is at the top of the trajectory. All statements refer to the basketball. Coordinate system: the x-axis is horizontal and points to the right, the y-axis is vertical and points up. (Neglect air friction.) The speed at R is .... that at Q. The acceleration at R is .... that at Q. The x-component of the velocity at S is .... that at Q. The y-component of the velocity at R is .... at Q. (I have tried this one at hreater than as well and it was still wrong). The y-component of the acceleration at S is .... zero. These answers are wrong, but I don't know which ones? Can anyone help me. Isn't acceleration always the same and the velocity is zero at the top.

Explanation / Answer

1. Correct. The speed at R is equal to the speed at Q because of the parabolic motion of the ball, and they are equadistant from Q, which is the apex of the motion.

2. Correct. The acceleration of the ball at R is the same as at Q because at any point in the parabola, the ball is accelerating down at 9.8 m/s/s (gravity).

3. Correct. The x component will be the same at Q as it is at R, not negative. The x velocity would be negative if it were moving to the left.

4. Incorrect. Well, by process of elimination, the answer would be 'equal to'...

5. Incorrect. When the ball is at the apex, its acceleration is completely represented by the y component and is -9.8 m/s/s due to gravity. Therefore, the acceleration at S is 'less than' 0.

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