Arocket, which is in deep space and initially at rest relative to an inertial reference frame, has a mass of 56.6 × 105 kg, of which 8.50 × 105 kg is fuel. the rocket engine is then fired for 240 s, during which fuel is consumed at the rate of 350 kg/s. the speed of the exhaust products relative to the rocket is 2.38 km/s.
(a) what is the rocket's thrust? after the 240 s firing, what are
(b) the mass and
(c) the speed of the rocket?

b) 5546000 kg

c) 48.42 m/s

Explanation:

Mass of fuel = 8.5×10⁵ kg

= Mass of ship = 56.6×10⁵ kg

R = Burn rate = 350 kg/s

= Speed of the exhaust products relative to the rocket = 2.37 km/s

Thrust

Thrust is 833000 N

Mass of fuel consumed in 240 s

350×240 = 84000 kg

Mass of ship after 240 s

Mass of ship after 240 s is 5576000 kg

Speed of rocket

The speed of the rocket after 240 s is 35.58 m/s

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.