Answer:
4.5s
Explanation:
A sports car accelerates from zero to 30 mph in 1.5 s.
Answer:
619.8 N
Explanation:
The tension in the string provides the centripetal force that keeps the rock in circular motion, so we can write:

where
T is the tension
m is the mass of the rock
v is the speed
r is the radius of the circular path
At the beginning,
T = 50.4 N
v = 21.1 m/s
r = 2.51 m
So we can use the equation to find the mass of the rock:

Later, the radius of the string is decreased to
r' = 1.22 m
While the speed is increased to
v' = 51.6 m/s
Substituting these new data into the equation, we find the tension at which the string breaks:

Answer:
D) directly, inversely
Explanation:
The energy of a photon of light is directly proportional to its frequency and inversely proportional to its wavelength.
Frequency is the number of waves that passes through a point per unit of time.
Wavelength is the is the distance between successive crests or troughs on a wave.
Mathematically, frequency is related to wavelength and velocity using;
Energy = h x f
where h is the Planck's constant
f is the frequency
Since c = f ∧
where f is the frequency of the wave
∧ is the wavelength of the wave
c is the speed of light
So;
f = c/∧
Therefore;
E = 
From the equation, we see an inverse relationship between E and wavelength and a direct one with frequency.