Answer:
The speed with which the man flies forward is 5.5 m/s
Explanation:
The mass of the man = 100 kg
The mass of the scooter = 10 kg
The speed with which the man was traveling on the scooter = 5 m/s
The speed of the scooter after it hits the rock = 0 m/s
Let v represent the speed with which the man flies forward
The formula for momentum, P, is P = Mass × Velocity
The conservation of linear momentum principle is, the total initial momentum = The total final momentum, therefore, we have;
The total initial momentum = (100 kg + 10 kg) × 5 m/s = 550 kg·m/s
The total final momentum = 100 kg × v + 10 kg × 0 m/s = 100 kg × v
When the momentum is conserved, we have;
550 kg·m/s = 100 kg × v
∴ v = 550 kg·m/s/(100 kg) = 5.5 m/s.
The speed with which the man flies forward = v = 5.5 m/s
So, there should be two forces acting on the refrigerator: the applied force and the friction force.
The question mentioned that the friction force was set to zero, so the only effective force now would be the applied force.
We have an applied force of 400 N to the right, this means that:
<span>The magnitude of the net force is 400, directed to the right.</span>
This question apparently wants you to get comfortable
with E = m c² . But I must say, this question is a lame
way to do it.
c = 3 x 10⁸ m/s
E = m c²
1.03 x 10⁻¹³ joule = (m) (3 x 10⁸ m/s)²
Divide each side by (3 x 10⁸ m/s)²:
Mass = (1.03 x 10⁻¹³ joule) / (9 x 10¹⁶ m²/s²)
= (1.03 / 9) x (10⁻¹³ ⁻ ¹⁶) (kg)
= 1.144 x 10⁻³⁰ kg . (choice-1)
This is roughly the mass of (1 and 1/4) electrons, so it seems
that it could never happen in nature. The question is just an
exercise in arithmetic, and not a particularly interesting one.
______________________________________
Something like this could have been much more impressive:
The Braidwood Nuclear Power Generating Station in northeastern
Ilinois USA serves Chicago and northern Illinois with electricity.
<span>The station has two pressurized water reactors, which can generate
a net total of 2,242 megawatts at full capacity, making it the largest
nuclear plant in the state.
If the Braidwood plant were able to completely convert mass
to energy, how much mass would it need to convert in order
to provide the total electrical energy that it generates in a year,
operating at full capacity ?
Energy = (2,242 x 10⁶ joule/sec) x (86,400 sec/day) x (365 da/yr)
= (2,242 x 10⁶ x 86,400 x 365) joules
= 7.0704 x 10¹⁶ joules .
How much converted mass is that ?
E = m c²
Divide each side by c² : Mass = E / c² .
c = 3 x 10⁸ m/s
Mass = (7.0704 x 10¹⁶ joules) / (9 x 10¹⁶ m²/s²)
= 0.786 kilogram ! ! !
THAT should impress us ! If I've done the arithmetic correctly,
then roughly (1 pound 11.7 ounces) of mass, if completely
converted to energy, would provide all the energy generated
by the largest nuclear power plant in Illinois, operating at max
capacity for a year !
</span>
