Answer:
1.78 J
Explanation:
Find the spring coefficient using Hooke's law:
F = k Δx
23 N = k (0.20 m − 0.14 m)
k = 383.33 N/m
The work is the change in energy:
W = PE₂ − PE₁
W = ½ kx₂² − ½ kx₁²
W = ½ k (x₂² − x₁²)
W = ½ (383.33 N/m) ((0.17 m)² − (0.14 m)²)
W = 1.78 J
Answer:
19.09 m/s
Explanation:
u = 0, h = 18.6 m
Use third equation of motion
v^2 = u^2 + 2 g h
v^2 = 0 + 2 x 9.8 x 18.6
v = 19.09 m/s
having to push a rough and heavy box across the floor to move it
Explanation:
Friction is not a useful force because we have to exert even more force to push a body that is rough and heavy across the floor to move it.
- Frictional force is a force that opposes the motion of a body.
- It costs more and uses more energy to push a rough and heavy box on surface because of friction.
- This wastes energy in systems that deals with pushing.
Friction is useful in that:
- the heat energy produced when two surfaces rub together is very useful.
- the friction between your feet and the floor keeping you from slipping and makes walking possible.
- the tread on tires helping the moving vehicle slow down and stop when necessary.
learn more:
Friction brainly.com/question/7174363
#learnwithBrainly
Answer:
9.66 x 10^-6 m
Explanation:
Use the Wein's displacement law
Where, b is the Wein's constant
b = 2.898 x 10^-3 meter-kelvin
So, λm x 300 = 2.898 x 10^-3
λm = 9.66 x 10^-6 m
