The roof of a two-story house makes an angle of 30°with the horizontal. a ball rollingdown the roof rolls off the edge at a speed of 5.0m/s. the distance to the ground fromthat point is 7.0 m. (a) how long is theball in the air? (b) how far from thebase of the house does it land? (c) what is its speedand direction just before landing?

Answer

angle made by the horizontal = 30°

velocity  =  5 m/s

distance = 7 m

Vertical component (V y) = 5 sin (30°) = 2.5 m/s

Horizontal component(V x) = 5 cos (30° ) = 4.33 m/s

Applying

t = 0.967 s

b) Distance from base

        =

        =

        = 2.42 m

c) You can find final vertical velocity

V= u + gt

V = 9.8 × 0.967

v = 9.48 m/s

Final velocity =

v = 8.433 m/s

Final angle

θ = 65.41°

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.

+15-35=-20

going in opposite directions