Answer:
-4m/s
Explanation:
use the formula
where f-force
m-mass
a-accleration
so
1kN=1000N
so apply
4000=1000×a
a=4m/s
(the negative is because the car was braking)
Answer:
c) The wavelength decreases but the frequency remains the same.
Explanation:
Light travels at different speed in different mediums.
Refractive index is equal to velocity of the light 'c' in empty space divided by the velocity 'v' in the substance.
Or ,
n = c/v.
<u>The frequency of the light does not change but the wavelength of the light changes with change in the speed.</u>
c = frequency × Wavelength
Frequency is constant,
The formula can be written as:
n = λ / λn.
Where,
λn is the wavelength in the medium
λ is the wavelength in vacuum
<u>When the light travels to glass, it speed slows down and also the wavelength decreases as both are directly proportional. There will be no effect on frequency.</u>
Answer:
Atomic number of calcium is 20.
Answer:
123.48J
Explanation:
Given parameters:
Mass of the ball = 2.8kg
Height = 4.5m
Unknown:
Potential energy = ?
Solution:
The potential energy is the energy due to the position of a body. It is mathematically given as;
P.E = mgh
m is the mass
g is the acceleration due to gravity
h is the height
Now insert the parameters and solve;
P.E = 2.8 x 4.5 x 9.8 = 123.48J
Answer:
If a car skids 66 ft on wet concrete, it will move at 243 ft/s when the brake is applied.
Explanation:
To determine how fast the car was moving, after skidding, the formula below is used:
V = √32*fd
V is the car's speed (ft/s)
d is skid length (ft) = 66 ft
f is the coefficient of friction determined by the material the car was skidding on.
Coefficient of friction for wet concrete is 0.65
V = √32*fd
V = √32 *0.65* 66
V = 242.679 ft/s ≅ 243 ft/s (nearest whole number)
If a car skids 66 ft on wet concrete, it will move at 243 ft/s when the brake is applied.
