Question

so my assignment is to answer 4/6 questions and I forgot how to do 4 of them. the ones I want help in answering are: A 5kg ball is on top of the school building at a height of 40m above the ground. : 4 partsA. calculate the potential energy of the ball at that height.B. how much power would it take to get the ball from the ground to that height in 1 minute.C. If it is dropped, what type of energy will the ball have as it approaches the ground.D. at what speed will the ball hit the ground

Answer 1

Given data

*The given mass of the ball is m = 5 kg

*The given height above the ground is h = 40 m

*The value of the acceleration due to the gravity is g = 9.8 m/s^2

*The given time is t = 1 minute = 60 s

(a)

The formula for the potential energy of the ball is given as

`U_p=mgh`

Substitute the known values in the above expression as

`\begin{gathered} U_p=(5)(9.8)(40)_{} \\ =1960\text{ J} \end{gathered}`

Hence, the potential energy of the ball is U_p = 1960 J

(b)

The formula for the power is given as

`P=(mgh)/(t)`

Substitute the known values in the above expression as

`\begin{gathered} P=(5*9.8*40)/(60) \\ =32.66\text{ W} \end{gathered}`

Hence, the power is P = 32.66 W

(c)

When the ball is dropped from the height, the ball possess the kinetic energy. As the ball is moving or approaching with a speed towards the ground.

(d)

The formula for the speed of the ball hit the ground is given by the conservation of energy as

`\begin{gathered} U_p=U_k \\ mgh=(1)/(2)mv^2 \\ v=\sqrt[]{2gh} \end{gathered}`

Substitute the known values in the above expression as

`\begin{gathered} v=\sqrt[]{2*9.8*40} \\ =28\text{ m/s} \end{gathered}`

Hence, the speed of the ball hit the ground is v = 28 m/s