KE = 1/2mv^2
m = 2000
v = 30m/s
1/2*2000*30^2=
1000*900 = 900,000kgm^2/s^2
Answer:
Explanation:
Question 1
An arrow weighing 20g shortly after firing has a speed of 50m / s. Calculate the work done by the athlete. What is the potential energy of the elasticity of the tensed string?
mass m = 20g = 20/1000 = 0.02kg
speed v = 50m / s
P.E = K.E = ½mv²
P.E = ½ × 0.02 × 50²
P.E = 25 J
work done = P.E = 25J
Qestion 2
A 80 kg athlete stood on a trampoline with a coefficient of elasticity of k = 2 kN / m. As far as the edge of the trampoline lowers.
force of elasticity
F = -kx
x = F / k
in our case F will be the force of pressure or gravity
F = mg
g is gravitational acceleration, and according to Newton's second law, acceleration is force through mass - unit of force N, unit of mass kg. Acceleration either in m / s ^ 2 or N / kg
F = 80kg * 10N / kg = 800 N
x = 800N / -2000N = -0.4
The trampoline will lower, so from the level by 0.4 meters and hence this minus
Answer: D
Explanation:
First, we know that the acceleration is defined as the ratio of change of the velocity.
This means that, if we have a change in the velocity, then we also have acceleration.
And by Newton's second law we know that:
F = m*a
Force equals mass times acceleration.
So if we have acceleration different than zero, then we should also have force different than zero.
So we must have a nonzero net force acting on it.
The correct option is D
Answer:
2805 °C
Explanation:
If the gas in the tank behaves as ideal gas at the start and end of the process. We can use the following equation:
The key issue is identify the quantities (P,T, V, n) in the initial and final state, particularly the quantities that change.
In the initial situation the gas have an initial volume , temperature , and pressure ,.
And in the final situation the gas have different volume and temeperature , the same pressure ,, and the same number of moles ,.
We can write the gas ideal equation for each state:
and , as the pressure are equals in both states we can write
solving for
(*)
We know = 935 °C, and that the (the complete volume of the tank) is the initial volume plus the part initially without gas which has a volume twice the size of the initial volume (read in the statement: the other side has a volume twice the size of the part containing the gas). So the final volume
Replacing in (*)
Voltage is potential energy per coulomb (J/C). So use the voltage and charge on an electron to get E=V•Q=1.5e8•1.602e-19=2.4e-11J