Answer:
áp dụng công thức v = s/t
s là dộ dài qduong
v là vận tốc
t là thời gian
xuyên suốt 2 câu hỏi đều dùng công thức này
Explanation:
Answer:
4.42 x 10⁷ W/m²
Explanation:
A = energy absorbed = 500 J
η = efficiency = 0.90
E = Total energy
Total energy is given as
E = A/η
E = 500/0.90
E = 555.55 J
t = time = 4.00 s
Power of the beam is given as
P = E /t
P = 555.55/4.00
P = 138.88 Watt
d = diameter of the circular spot = 2.00 mm = 2 x 10⁻³ m
Area of the circular spot is given as
A = (0.25) πd²
A = (0.25) (3.14) (2 x 10⁻³)²
A = 3.14 x 10⁻⁶ m²
Intensity of the beam is given as
I = P /A
I = 138.88 / (3.14 x 10⁻⁶)
I = 4.42 x 10⁷ W/m²
Answer:
A
Explanation:
A consensus is when you come to an agreement
The car has a 12 mile head start, going 80 mph, so his distance is:dcar=80∗t+12
The is going at 108 mph, so his distance is:dcop=108t
Setting them equal to each other we get:80t+12=108t⇒12=28t⇒t=1228=37
So 3/7 of an hour.about 25.7 mins.
