# Position and Movement Question

A man standing in a stationary lift releases a stone. The stone takes t seconds to reach the floor of the lift. If the lift is moving downwards with constant velocity instead of being stationary

A.The stone takes a time less than t seconds to reach the floor

B.The stone also takes a time of t seconds to reach the floor

C.The stone takes a time greater than t seconds to reach the floor

D.The stone may of may not reach the ground depending on the speed the lift

Ans = B

why the ans = B ?

### 2 個解答

• 匿名
1 十年前
最愛解答

A man standing in a stationary lift releases a stone. The stone takes t seconds to reach

the floor of the lift. If the lift is moving downwards with constant velocity instead of being

stationary

A.The stone takes a time less than t seconds to reach the floor

B.The stone also takes a time of t seconds to reach the floor

C.The stone takes a time greater than t seconds to reach the floor

D.The stone may of may not reach the ground depending on the speed the lift

Since the lift moves at uniform velocity,

the net force is only the gravititional force

As now is on the ground,

the stone also takes a time of t seconds to reach the floor

Since there is only gravitational force acting on it.

Ans = B

資料來源： EASON MENSA
• Karin
Lv 6
1 十年前

If the lift is moving downwards with constant velocity , there is no accelartion acting on the stone.

When the stone is released, it is only acted by the gravitational acceleration only.

Hence, it is the same case as the lift being stationary