Answer:

%
%
Explanation:
From the exercise we know two information. The real speed and the experimental measured by the speedometer

Since the speedometer is only accurate to within 0.1km/h the experimental speed is

Knowing that we can calculate Kinetic energy for the real and experimental speed


Now, the potential error in her calculated kinetic energy is:

%
%
Answer: 8000N
Explanation: since it is frictionless that means it has 100% efficiency therefore the mechanical advantage is 1 meaning the load equals to the effort
Answer:

Explanation:
Given:
- mass of solid cylinder,

- diameter of cylinder,

- mass of bucket of water,

<em>When the bucket is released to fall in the well, it fall under the acceleration due to gravity.</em>
We have formula for angular acceleration as:

where:
g = acceleration due to gravity
r = radius of the cylinder


Answer: having to push a rough and heavy box across the floor to move it
Explanation:
The Friction force is any force that is in opposite direction of the motion of an object or fluid due to the contact of this object or fluid with other bodies.
In this sense, there are different types of friction force thath are useful in different situations:
-The <u>Static friction force</u> prevents surfaces from slipping across each other. For example, the friction between your feet and the floor keeping you from slipping.
-The <u>kinetic friction force</u> as the force that helps the tires in a moving vehicle to slow down and stop when necessary.
However, if you want to push a heavy box across the floor to move it, the friction force will not be useful at all.
Answer:
v₁ = -0.8087 m / s
Explanation:
To solve this problem we can use the conservation of momentum, for this we define a system formed by the man, the skateboard and the brick, therefore the force during the separation is internal and the momentum is conserved
Initial instant. When they are united
p₀ = 0
Final moment. After throwing the brick
= (m_man + m_skate) v1 + m_brick v2
the moment is preserved
p₀ = p_{f}
0 = (m_man + m_skate) v₁ + m_brick v₂
v₁ = -
the negative sign indicates that the two speeds are in the opposite direction
let's calculate
v₁ = -
v₁ = -0.8087 m / s