Answer:
External force on him will be 112 N
Explanation:
We have given the mass of the sprinter m =70 kg
Acceleration of the sprinter 
We have to find the net external force
According to second law of motion force = mass ×acceleration
Force is dependent on the mass and acceleration
So 
So external force will be 112 N
Answer:
the rock will continue at the same speed unless it is affected by another force such as gravity and so if you threw it it will continue to move unless affected by a force
Explanation:
this is because Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.
The conservation of energy always holds true even when not clearly observable in machines that are less than 100% efficient. More often than not a machine will suffer energy losses (e.g. consider for a cooling fan: friction between the rotating blades, drag resistance in the air the fan is pushing around, resistance in the wire, and heat radiating/conducting away from the circuitry).
Let us say that Cp is the specific heat of the metal object.
Then we do a heat balance (heat lost by metal = heat gained by water):
- 19g * Cp * (22degC – 96degC) = 75g * 4.184J/g degC * (22degC
– 18degC)
<span>Cp = 0.893 J/g degC</span>
