Explanation:
Speed is the rate of change of distance with time. It is a scalar quantity with magnitude both no direction.
Speed = 
The unit is m/s or km/hr or mile/hr
Distance covered is simply the length of the path traveled.
The unit is m or km or miles
Time taken is the duration of an event.
The unit is seconds or minutes or hour.
Work done = force x distance
work done = 15 x 3
work done = 45J
Answer:
58.32 N
Explanation:
Area of a circle = 
where r is the radius of the circle.
The cylinder has a radius of 0.02 m, its area is;
=
= 
x 
= x 0.0004
= 1.2571 x 
Area of the cylinder is 0.0013 
.
The safety valve has a radius of 0.0075 m, its area is;
=
= x 
= x 5.625 x 
= 1.7679 x 
Area of the valve is 0.00018 .
From Hooke's law, the force on the safety valve can be determined by;
F = ke
= 950 x 0.0085
= 8.075 N
Minimum force, 
, required can be determined by;
= 
= 
= 
= 58.32
The minimum force that must be exerted on the piston is 58.32 N.
Destructive force
It’s a force that slowly wears away mountains and other features on earths surface, such as erosion.
Explanation:
neutron stars have diameters of about 20km and they are denser than the earth. A rotating neutron star pulsating electromagnetic beam is a named a pulsars but not all neutron stars are pulsars.
Only three of hundreds of known pulsar are found in supernova remnants because as neutron stars gets older, they lose energy and starts to decrease their rotational speeds and the neutron star could not radiate particles and energy for long as a pulsar does. there are less existing pulsars compared to supernova explosion rate because the life time of pulsars is obout 10×10^6 years after the neutron can no longer spin at high speeds to produce beams of particles and energy, almost all the pulsars are older and spin slow to produce light of visible wavelength or X-ray wavelengths and we only get a pulse of radiation from a neutron star as a pulsar as the beam sweeps over earth.
