1. a partially filled balloon that has helium in it is released off the top of a 400m building. because of the helium, the acceleration due to gravity is decreased to 2.5 m/s2. how long does it take for the balloon to reach the ground ?
2. a rubber ball travelling at 10 m/s for 4 seconds at 450 north of east collides with a wall. the ball reflects off the wall at the same speed and continues to move for 3 seconds. what is the displacement of the ball?

How does the image distance (di) of a convex lens compare with the image distance of a concave lens? a. the image distance of the convex lens is positive, and that of the concave lens is negative. b. both are negative for a virtual image. c. both are positive for a virtual image d. the image distance of the convex lens is negative, and that of the concave lens is positive.

Compare the horizontal displacement of the two balls as they travel to the ground. what do you observe?

Amass attached to a spring is displaced from its equilibrium position by 5cm and released. the system then oscillates in simple harmonic motion with a period of 1s. if that same mass–spring system is displaced from equilibrium by 10cm instead, what will its period be in this case? a mass attached to a spring is displaced from its equilibrium position by and released. the system then oscillates in simple harmonic motion with a period of . if that same mass–spring system is displaced from equilibrium by instead, what will its period be in this case? a) 0.5sb) 2sc) 1sd) 1.4s