Answer:
a.The 60 km/HR car
Explanation:
Kinetic Energy: This can be defined as the energy of a body due to motion. The S.I unit of kinetic energy is Joules (J).
It can be expressed mathematically as
Ek = 1/2mv²......................... Equation 1
Where Ek = kinetic energy, m = mass, v = velocity.
(i) A car travelling at 30 km/hr, with a mass of m,
Ek = 1/2(m)(30)²
Ek = 450m J.
(ii) A car travelling at 60 km/hr, with a mass of m/2
Ek = 1/2(m/2)(60)²
Ek = 900m J.
Thus , the car travelling at 60 km/hr at half mass has a greater kinetic energy to the car traveling at 30 km/hr at full mass.
The right option is a.The 60 km/HR car
Answer:
period in case 2 is times the period in case 1
Explanation:
The period of oscillation of a spring is given by:
where
m is the mass hanging on the spring
k is the spring constant
Therefore, in order to compare the period of the two springs, we need to find their m/k ratio.
We know that when a mass hang on a spring, the weight of the mass corresponds to the elastic force that stretches the spring by a certain amplitude A:
So we find
The problem tells us that the amplitude of case 1 is d, while the amplitude in case 2 is 2d. So we can write:
- for case 1:
- for case 2:
And by comparing the two periods, we find:
So, the period of oscillation in case 2 is times the period of oscillation in case 1.
Wavelength = (speed) / (frequency)
= (3 x 10^8 m/s) / (2.4 x 10^9 Hz)
= 0.125 meter.
The quarter-wavelength antenna needs to be about 3 cm long. It fits fine inside the 9-cm case of the phone.
At the bottom left,
Increasing potential energy.
At ascending,
Increasing kinetic energy.
At the peak,
Greatest potential energy.
At the descending,
Greatest kinetic energy.