Answer
D) burning a candle
Explanation
When burning a candle no new substance is form.
We have both physical and chemical change occuring.
Physical part: Melting of the solid wax and evaporation of the liquid forms the physical change.
Chemical part: burning of the wax vapour forms the chemical change.
Answer:
(i) The period, T is 0.25 s
(ii) The angular velocity, ω is 25.136 rad/s
(iii) The linear velocity is, v is 50.27 m/s
Explanation:
Given;
number of revolution of the particle, N = 240 revolutions per minutes
radius of the circle, R = 2m
(i) The period is given by;
where;
ω is angular velocity
(ii) angular velocity, ω = 25.136 rad/s
(iii) linear velocity is given by;
v = ωR
v = (25.136 rad/s) x (2 m)
v = 50.27 m/s
Answer: Mechanical waves must travel through a medium, but electromagnetic waves do not require a medium to travel.
Explanation: 'Electromagnetic' waves do not need any medium to travel whereas 'mechanical waves' need a medium or matter for transmission. Electromagnetic waves are produced by the 'vibrations' of the charged particles. They can even travel in vacuum.
On the contrary, mechanical waves are caused by the 'wave amplitude'. Mechanical wave can travel in solid, liquid and gas and are considered to be periodic disturbance.
Answer:
F₁ = 4,120.2 N
F₂ = 3,924N
Explanation:
1) Balance of angular momentum around the end where F₁ is applied.
F₂ × 0.5m - F₁ × 0 = mass × g × 1m
⇒ F2 × 0.5 m= 20 kg × 9.81 m/s² × 1 m = 1,962 N×m
F₂ = 196.2 Nm / 0.5m = 3,924 N
2) Balance of forces
F₁ - F₂ = mg
F₁ = F₂ + mg = 3,924N + 20kg (9.81 m/s²) = 4,120.2 N