please can u check my answer
Here are the questions:
1. A 0.45 kg book is resting on a dessktop 0.64 m high. Calculate the book's potential energy relative to
a)the desktop? b)the floor.
2. A 0.636 kg basketball has a potential energy of 19J at the basket. How high is the ball from the floor?
3. A hockey puck has a potential energy of 2.3J when it is held by a referee at a height of 1.4 m above the rink surface. calculate the mass of puck?
My solutions:(used Eg=mgh to get all solutions)
1. a) 2.8J b) 0
2. h=31m
3. 0.6176 kg
I think you reversed the answers on 1.
2. mgh=19
h= 19/(.636*9.8) didn't you miss the decimal place?
3. mgh=PE
m= 2.3/(1.4*9.8) not your answer.
when i divided 2.3/(1.4*9.8) i got 0.1676
and for quesiton 1 do u mean that a) will be 0J sinse it is rest on the desktop and b) will be 2.8 J
yes, and yes.
To check your answers, let's go through each question and calculation step-by-step.
1. a) To find the potential energy relative to the desktop, you correctly used the formula: Eg = mgh
Given:
Mass of the book (m) = 0.45 kg
Height from the desktop (h) = 0.64 m
Plugging in the values:
Eg = (0.45 kg) * (9.8 m/s^2) * (0.64 m)
Eg = 2.8272 J
Your answer of 2.8 J is correct.
1. b) To find the potential energy relative to the floor, we can use the same formula, but this time considering the total height from the floor.
Given:
Height from the desktop (h) = 0.64 m
Calculating the total height:
Total height = height from the desktop + height of the desk
Suppose the height of the desk is H. We are not given the exact value, but it's usually negligible compared to the height of the book. So we can assume H ≈ 0.
Total height ≈ 0.64 m + 0 m
Total height ≈ 0.64 m
Now let's calculate the potential energy relative to the floor using Eg = mgh.
Eg = (0.45 kg) * (9.8 m/s^2) * (0.64 m)
Eg = 2.8272 J
Your answer of 0 J is incorrect. The correct answer is 2.8 J.
2. To find the height of the basketball from the floor, given its potential energy, we can rearrange the formula Eg = mgh and solve for h.
Given:
Potential energy (Eg) = 19 J
Mass of the basketball (m) = 0.636 kg
Acceleration due to gravity (g) = 9.8 m/s^2 (approximated)
Rearranging the formula:
h = Eg / (mg)
Plugging in the values:
h = 19 J / [(0.636 kg) * (9.8 m/s^2)]
h ≈ 31.176 m
Your answer of h = 31 m is correct.
3. To find the mass of the hockey puck, given its potential energy and height, we can rearrange the formula Eg = mgh and solve for m.
Given:
Potential energy (Eg) = 2.3 J
Height (h) = 1.4 m
Acceleration due to gravity (g) = 9.8 m/s^2 (approximated)
Rearranging the formula:
m = Eg / (gh)
Plugging in the values:
m = 2.3 J / [(9.8 m/s^2) * (1.4 m)]
m ≈ 0.157 kg
Your answer of m ≈ 0.6176 kg is incorrect. The correct answer is m ≈ 0.157 kg.
In summary, your answers for questions 1a), 2, and 3 are correct. However, your answer for question 1b) is incorrect.