Answer:
When white light strikes a colored opaque object, some colors of light are absorbed and some are reflected. ... Some of the colors are absorbed and some are reflected. When white light shines on a white object, all colors are reflected. When white light strikes a black object, all colors are absorbed.
Explanation:
Answer:

Explanation:
Impulse on an object is given by
.
However, it's also given as change in momentum (impulse-momentum theorem).
Therefore, we can set the change in momentum equal to the former formula for impulse:
.
Momentum is given by
. Because the truck's mass is maintained, only it's velocity is changing. Since the truck is being slowed from 26.0 m/s to 18.0 m/s, it's change in velocity is 8.0 m/s. Therefore, it's change in momentum is:
.
Now we plug in our values and solve:
(two significant figures).
Answer:
Stretch can be obtained using the Elastic potential energy formula.
The expression to find the stretch (x) is 
Explanation:
Given:
Elastic potential energy (EPE) of the spring mass system and the spring constant (k) are given.
To find: Elongation in the spring (x).
We can find the elongation or stretch of the spring using the formula for Elastic Potential Energy (EPE).
The formula to find EPE is given as:

Rewriting the above expression in terms of 'x', we get:

Example:
If EPE = 100 J and spring constant, k = 2 N/m.
Elongation or stretch is given as:

Therefore, the stretch in the spring is 10 m.
So, stretch in the spring can be calculated using the formula for Elastic Potential Energy.
Answer:
a) F = 1.26 10⁵ N, b) F = 2.255 10³ N, c) F_ {soil} = 3078 N
Explanation:
For this exercise we will use the relationship between momentum and moment
I = Δp
F t = p_f -p₀
a) with stiff legs, final speed is zero, initial velocity is down
Ft = 0-p₀
F = m v / t
let's calculate
F = 84.0 6.82 / 4.56 10⁻³
F = 1.26 10⁵ N
b) bending the legs
let's calculate
F = 84.0 6.82 / 0.254
F = 2.255 10³ N
c) It is requested to calculate the force of the ground on the man
∑ F = F_soil -W
F_soil = F + W
F_ {soil} = 2.255 103 + 84 9.8
F_ {soil} = 3078 N
Answer:

Explanation:
The universal law of gravitation is defined as:
(1)
Where G is the gravitational constant, M and m are the masses of the two objects and r is the distance between them.
The centripetal force can be found by means of Newton's second law:
(2)
Since it is a circular motion, the acceleration can be defined as:
(3)
Where v is the velocity and r is the orbital radius.
Replacing equation (3) in equation (2) it is gotten:
(4)
Hence,
Then, v can be isolated:
So the relationship between speed and orbital radius is given by the expression 