An impala is an African antelope capable of a remarkable vertical leap. In one recorded leap, a 25.5 kg impala went into a deep crouch, pushed straight up for 0.21 s, and reached a height of 2.5 m above the ground. To achieve this vertical leap, with what force did the impala push down on the ground?

The impala pushed down the ground with a force of 37.49N

Explanation:

The force at which the impala pushed down the ground can be calculated for using the Newton's second law of motion,

Force = mass × acceleration

Force = mass ×(velocity/time)

Given mass = 25.5kg

Time = 0.21seconds

To get the velocity, we will use one of the equation of motions;

Using v² = u²+2gH

where;

H is the height reached from the ground = 2.5m

g = 9.81m/s²

u is the initial velocity = 0m/s

v is the final velocity=?

Substituting this values to get the final velocity v;

v² = 0²+2(9.81)(2.5)

v² = 49.05

v = √49.05

v = 7.0m/s

Substituting this velocity into the formula for force we have;

Force = 25.5×(7.0/0.21)

Force = 25.5 × 1.47

Force = 37.49N

The impala pushed down the ground with a force of 37.49N

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.

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