K.E = 1/2 mv²
800 = 1/2 ×12 ×v²
800 = 6 v²
800 / 6 = v²
= 133.4 =v²
√133.4 = √v²
11.5 = v²
I hope this answer is correct.
Answer:
Frequency, 
Explanation:
Visible red light has a wavelength of 680 nanometers (6.8 x 10⁻⁷ m). The speed of light is 3.0 x 10 ⁸ m / s. What is the frequency of visible red light?
It is given that,
Wavelength of a visible red light is, 
Speed of light is, 
We need to find the frequency of visible red light. It can be calculated using below relation.

So, the frequency of visible red light is
.
I just took it 100% 11/11
1.D
2.A
3.A
4.A
5.B
6.C
7.D
8C
9A
10B
11C
Mass.
Because mass doesn't depend on weight but weight depends on mass.