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
When a vacuum pump removes the air within the can, there is no more air molecules bombarding the inner surface of the can. Since the inner pressure=0, the atmospheric pressure will crush the can. Atmosoheric pressure is usually =1.3*10^5Pa.
Answer:
α = 1215.71 rad/s²
Explanation:
The angular acceleration of an object is defined as the time rate of change of angular velocity of he object. The formula for the angular acceleration of an object is given as follows:
α = (ωf - ωi)/Δt
where,
α = angular acceleration of the disk = ?
ωf = Final Angular Velocity = 0 rad/s (Since disk finally stops)
ωi = Initial Angular Velocity = (5050 rpm)(2π rad/rev)(1 min/60 s)
ωi = 528.83 rad/s
Δt = time interval = 0.435 s
Therefore,
α = (0 rad/s - 528.83 rad/s)/(0.435 s)
α = - 1215.71 rad/s²
here, negative sign indicates that the direction of acceleration is opposite to the direction of angular velocity or the angular motion. So, the magnitude of acceleration will be:
<u>α = 1215.71 rad/s²</u>
From Doppler effect we have that the frequency observed for the relation between the velocities is equivalent to the frequency observed. That is mathematically,

Here,
Speed of sound in water 
The Dolphin swims directly away from the observer with a velocity 
Observed frequency of the clicks produced by the dolphin 
Replacing we have,




Therefore the frequency emitted by the dolphin is 2754.61Hz
(a)
The formula is:
∑ F = Weight + T = mass * acceleration
as the elevator and lamp are moving downward, I choose downward forces to be
positive.
Weight is pulling down = +(9.8 * mass)
Tension is pulling up, so T = -63
Acceleration is upward = -1.7 m/s^2
(9.8 * mass) + -63 = mass * -1.7
Add +63 to both sides
Add (mass * 1.7) to both sides
(9.8 * mass) + (mass * 1.7) = 63
11.5 * mass = 63
mass = 63 / 11.5
Mass = 5.48 kg
(b)
Since the elevator and lamp are going upward, I choose upward forces to be
positive.
Weight is pulling down = -(9.8 * 5.48) = -53.70
Acceleration is upward, so acceleration = +1.7
-53.70 + T = 5.48 * 1.7
T = 53.70 + 9.316 = approx 63 N
The Tension is still the same - 63 N since the same mass, 5.48 kg, is being accelerated
upward at the same rate of 1.7 m/s^2