A0.50 kilogram ball is held at a height of 20 meters. what is the kinetic energy of the ball when it reaches halfway after being released? a. 49 joules b. 98 joules c. 1.0 × 10^2 joules d. 1.1 × 10^2 joules

A. 49 joules

Step By Step Solution:

Via kinematic equations we can must first determine the velocity of this object after 10 meters (since halfway of 20 meters is 10).

Where the initial velocity is zero since it's held at a height of 20 meters, hence it's not moving initially, g is the average gravity on Earth 9.8 m/s^2 and d is the distance this object will travel so 10 meters. By plugging these values in we obtain:

And the equation for kinetic energy is :

So the kinetic energy halfway after being released is 49 joules.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

we're given that v₀ = 0 and a = 5.4 m/s². therefore, since v = at + v₀ for constant acceleration the equation for velocity is

after 28s,

m/s

which i would round to 150 m/s as my final answer