Respuesta :
Answer:
a) KINETIC ENERGY K = 0.045 J , b) POTENTIAL ENERGY U = 0.196 J ,
c) KINETIC ENERGY K = 9.45 10⁵ J, d) POTENTIAL ENERGY , U = 41.16 J ,
e) POTENTIAL ENERGY U = 154.84 J , f) ENERGY IS POTENTIAL U = 9.31 J
g) energy is POTENTIAL U = 189.336 J
Explanation:
a) The ball is moving with a speed, so it has KINETIC ENERGY
K = ½ m v²
K = ½ 10 10⁻³ 3²
K = 0.045 J
b) The ball is at a given height therefore it has POTENTIAL GRAVITATORY ENERGY
U = m g y
U = 10 10-3 9.8 2
U = 0.196 J
c) The ball has speed so it has KINETIC ENERGY
K = ½ m v²
K = ½ 2,100 30²
K = 9.45 10⁵ J
d) The baby carriage is at a height whereby the POTENTIAL ENERGY
U = mg h
U = 0.200 9.8 21
U = 41.16 J
e) the concrete block is at a height that has POTENTIAL ENERGY
U = m g h
U = 0.790 9.8 20
U = 154.84 J
f) the hood has height, the ENERGY IS POTENTIAL
U = 0.190 9.8 5
U = 9.31 J
g) The roller coaster has height and speed, therefore the mechanical energy has a scientific part and a potential part, in general the speed at the top of the mountain is very small, so we can consider that almost all the energy is POTENTIAL
The value they give allows calculating the potential energy
U = 9.660 9.8 2
U = 189.336 J
The answer to all the questions on potential energy and kinetic energy have been done below;
A) We are told that the ball is rolling. An object in motion has kinetic energy. Formula for kinetic energy is;
K = ½mv²
We have; m = 10 g = 0.01 kg and v = 3 m/s
K = ½ × 0.01 × 3²
K = 0.045 J
B) We are told that the ball is held at a height. This means it is at rest and any object at rest has Potential Energy. Formula for potential energy is;
PE = mgh
We have; m = 10g = 0.01 kg and h = 2 m
PE = 0.01 × 9.8 × 2
PE = 0.196 J
C) Like in A above, the ball is in motion. Thus, it has kinetic energy.
K = ½ × 2.1 × 30²
K = 945 J
D) The baby carriage is sitting at rest and therefore has potential energy.
PE = 0.2 × 9.8 × 21
PE = 41.16 J
E) The toy car is in motion and has kinetic energy. Thus;
K = ½ × 1.12 × 4²
K = 8.96 J
F) The cinder block is sitting at rest and has potential energy. Thus;
PE = 0.79 × 9.8 × 20
PE = 154.84 J
G) The bell is at the top of the tower and is at rest and thus has potential energy.
PE = 0.19 × 9.8 × 5
PE = 9.31 J
g) The rollercoaster is at the top at rest and so has potential energy.
PE = 9.66 × 9.8 × 2
PE = 189.336 J
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