The kinetic energy of a body moving at a speed of 10 m / s is equal to 1000 J. What is the body mass

20

Explanation:

Speed is 10 m/s

Kinetic energy is 1000joules

Mass is ?

Therefore the mass can be calculated as follows

K.E= 1/2mv^2

1000= 1/2 × m × 10^2

1000= 1/2 × m × 100

1000= 100m/2

2000= 100m

m= 2000/100

m= 20

Hence the mass is 20kg

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.