A Block Is Supported on a Compressed Spring, Which Projects

question 71

Multiple Choice

A block is supported on a compressed spring, which projects the block straight up in the air at velocity . The spring and ledge it sits on then retract. You can win a prize by hitting the block with a ball. When should you throw the ball and in what direction to be sure the ball hits the block? (Assume the ball can reach the block before the block reaches the ground and that the ball is thrown from a height equal to the release position of the block.)

• A)At the instant when the block leaves the spring, directed at the block
• B)At the instant when the block leaves the spring, directed at the spring
• C)At the instant when the block is at the highest point, directed at the block
• D)At the instant when the block is at the highest point, directed at the spring
• E)When the block is back at the spring's original position, directed at that position