There are two buildings with the same length on Earth and Bizarro World. A brick is released from the top of each building. On Earth, the brick reaches the ground in 5 secs while on Bizarro World it takes 7 secs. What can you say about the gravity on Bizarro World?

Question

Quizplus · Accepted Answer

Bricks in this scenario are falling from the same height (on different worlds), so the acting forces are gravity on earth and gravity on Bizarro World. The acceleration for any object moving under the sole influence of gravity on Earth is the gravitational constant which is 9.8 m/s². We'll solve this question in 2 steps. Step 1: Determine the height of the building. The basic equation for total distance traveled is d = V_i(t) + (0.5)a_e (t²). Since the object starts from rest, initial velocity is 0. Then the equation reduces to: d = (0.5) a_e (t²) d = displacement of the object (distance traveled) V_i = initial velocity t = time a_e = acceleration on earth a_b = acceleration on bizarre world Filling in the values d = (0.5)(9.8 m/s² )(5² s² ) d = (0.5)(9.8)(25)m d = (4.9)(25)m d = 122.5 meters. Step 2: Determine the rate of acceleration associated with gravity on Bizarro World. In this step, we'll back-trace what we did in Step 1. This time we know the total distance traveled in the Bizarro world; since the heights of the buildings are equal, we need to solve the same equation for a_b: d = (0.5)a_b(t²) Filling in the values 122.5m = (0.5) a_b (7²s²) 122.5m = (0.5)(a_b )(49s² ) 122.5m = (24.5s² )(a_b) Then a_b= 122.5m/(24.5s²) a_b= 5 m⁄s²

There Are Two Buildings with the Same Length on Earth