Answer:
d) 700 m/s
Explanation:
if k is the force constant and x is the maximum compression distance, then:
the potential energy the spring can acquire is given by:
U = 1/2×k×(x^2)
and, the kinetic energy system is given by:
K = 1/2×m×(v^2)
if Ki is the initial kinetic energy of the system, Ui is the initial kinetic energy of the system and Kf and Uf are final kinetic and potential energy respectively then, According to energy conservation:
initial energy = final energy
Ki +Ui = Kf +Uf
Ui = 0 J and Kf = 0J
Ki = Uf
1/2×m×(v^2) = 1/2×k×(x^2)
m×(v^2) = k×(x^2)
v^2 = k×(x^2)/m
= (500)×((21×10^-2)^2)/(19×10^-3 + 8)
= 2.75
v = 1.66 m/s
the v is the final velocity of the bullet block system, if m1 is the mass of bullet and M is the mass of the block and v1 is the initial velocity of the bullet while V is the initial velocity of the block, then by conservation linear momentum:
m1×v1 + M×V = v×(m1 + M) but V = 0 because the block is stationary, initially.
m1×v1 = v×(m1 + M)
v1 = v×(m + M)/(m1)
= (1.66)×(19×10^-3 + 8)/(19×10^-3)
= 699.86 m/s
≈ 700 m/s
Therefore, the velocity of the bullet just before it hits the block is 700 m/s.
The speed of light in that medium is 
.
<u>Explanation:</u>
It is known that the light's speed is constant when it travels in vacuum and the value is 
. When the light enters another medium other than vacuum, its speed get decreased as the light gets refracted by an angle.
The amount of refraction can be determined by the index of refraction or refractive index of the medium. The refraction index is measured as the ratios of speed of light in vacuum to that in the medium. It is represented as η = 
So, here η is the index of refraction of a medium which is given as 1.4, c is the light's speed in vacuum (
) and v is the light's speed in that medium which we need to find.
Thus the speed of light in that medium is 
Answer:
A. Both spheres land at the same time.
Explanation:
The horizontal motion doesn't affect the vertical motion. Since the two spheres have the same initial vertical velocity and same initial height, they land at the same time.
The correct option is this: KINETIC ENERGY JUST BEFORE REACHING THE GROUND IS LESS THAN THE GRAVITATIONAL POTENTIAL ENERGY AT THE TOP OF THE BUILDING.
When the object was on the top of the building, it has potential energy. This potential energy was converted to kinetic energy when the object started falling. In the process of falling, friction was present, which means that some of the energy will be converted to heat as a result of the friction. Therefore the kinetic energy of the falling object will be less than its potential energy, because some of the energy has been spent on friction.<span />
