Answer:
B. A car of mass 2000 kg with speed 7 m/s
Explanation:
The kinetic energy of an object is given by:
where m is the mass of the object and v is its speed.
From the formula, we see that the larger the mass and the speed of the object, the larger its kinetic energy. Among the choices given, we see that the car with largest mass and largest speed is car B, which has a mass of 2000 kg and speed of 7 m/s. Its kinetic energy is:
We can verify that the other cars have smaller kinetic energy. In fact:
- Car A: 
- Car C: 
- Car D: 
So, car B is the one which has most kinetic energy.
Answer:
pha của dao động là hàm bậc nhất của thời gian.
The woman weighs 100N now.
Explanation:
Given:
F is given as 400N
one full additional earth radius formed
To Find:
Weight of the woman=?
Solution:
We know that gravitational force is inversely proportional to the square of radius.
where
is the gravitational force
is the radius square
So when radius is doubled, the force becomes one fourth of the original.
Therefore 
Answer:
θ₂ = 35.26°
Explanation:
given,
refractive index of air, n₁ = 1
refractive index of glass, n₂ = 1.5
angle of incidence, θ₁ = 60°
angle of refracted light, θ₂ = ?
using Snell's Law
n₁ sin θ₁ = n₂ sin θ₂
1 x sin 60° = 1.5 sin θ₂
sin θ₂ = 0.577
θ₂ = sin⁻¹(0.577)
θ₂ = 35.26°
Hence, the refracted light is equal to θ₂ = 35.26°
The unit of frequency, kHz, is also equivalent to 1/kilosecond or 1/1000 seconds. The equation relating wavelength and frequency is:
c = wavelength*frequency, where c is known as the speed of light. But since we are dealing with ultrasound, we use the speed of sound. The speed of sound is dependent on the temperature. The correlation would be:
c = 331 + 0.6T = 331 + 0.6(20°C) = 343 m/s
Therefore,
343 = wavelength * 1/1000
wavelength = 343,000 meters
