First the velocity drops to zero in 1.2 secs. In those seconds it went upwards for 7.2 m, then it went from 87.2 to 0m. x-x0=v0*t+1/2*g*t^2 ergo t=sqrt(2x/g) that is 4.1761 s. Finally the total time required is 5.3761 s
Answer:
The electromagnetic force
Explanation:
The electromagnetic force is one of the four fundamental forces of nature. Namely, they are:
- Electromagnetic force: it is the force exerted between electrically charged particles (and between magnetic fields). The force can be either attractive (if the two charges have opposite signs) or repulsive (if the two charges have same sign), and it acts over an infinite range.
- Gravitational force: it is the force exerted between objects with mass. It is always attractive, and it also has an infinite range of action. It is the weakest of the four fundamental forces.
- Strong nuclear force: it is the force that acts between protons and neutrons inside the nucleus, and it is responsible for keeping the nucleus together and preventing it from breaking apart (due to the electrostatic repulsion between protons)
- Weak nuclear force: it is the force responsible for certains nuclear decays, such as the beta decay, in which a neutron turns into a proton, emitting an electron and an antineutrino.
Answer:
c)At a distance greater than r
Explanation:
For a satellite in orbit around the Earth, the gravitational force provides the centripetal force that keeps the satellite in motion:
where
G is the gravitational constant
M is the Earth's mass
m is the satellite's mass
r is the distance between the satellite and the Earth's centre
v is the speed of the satellite
Re-arranging the equation, we write
so we see from the equation that when the speed is higher, the distance from the Earth's centre is smaller, and when the speed is lower, the distance from the Earth's centre is larger.
Here, the second satellite orbit the Earth at a speed less than v: this means that its orbit will have a larger radius than the first satellite, so the correct answer is
c)At a distance greater than r
knowledge of first aid ... eg St John Ambulance, Red Cross etc. I think that everyone in a school should be taught First Aid.