Given the time, the final velocity and the acceleration, we can calculate the initial velocity using the kinematic equation A:

A skateboarder flies horizontally off a cement planter. After a time of 3 seconds (Δt), he lands with a final velocity (v) of −4.5 m/s. Assuming the acceleration is -9.8 m/s² (a), we can calculate the initial velocity of the skateboarder (v₀) using the kinematic equation A.

Given the time, the final velocity and the acceleration, we can calculate the initial velocity using the kinematic equation A:

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Via half-life equation we have:

Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes. By plugging those values in we get:

There is 6.25 grams left of Ra-229 after 12 minutes.
Answer:
All materials are superconducting at temperatures near absolute zero kelvin.
Explanation:
All materials are superconducting at temperatures near absolute zero kelvin is false concerning superconductors.
Answer:

Explanation:
This is a uniformly accelerated motion, so we can determine the deceleration of the car by using a suvat equation:

where
v is the final velocity
u is the initial velocity
a is the acceleration
s is the distance covered
For the car in this problem,
u = 27.8 m/s
v = 0
s = 17 m
Solving for a, we find the acceleration:
