1. There is a famous intersection in Kuala Lumpur, Malaysia, where thousands of vehicles pass each hour. A 750 kg Tesla Model S traveling south crashes into a 1250 kg Ford F-150 traveling east. What are the initial speeds of each vehicle before collision if they stick together after crashing into each other and move at an angle of 320 and a common velocity of 18 m/s.

Solution :

Let the positive is along the East and the positive direction is along the north.

Given :

Mass of the Tesla car, =

Mass of the Ford car,

Now let the initial velocity of Tesla car in the south direction be =

The initial momentum of Tesla car,

Let the initial velocity of Ford car in the east direction be =

So the initial momentum of the Ford car is

Therefore, the initial velocity of both the cars is

Now the final velocity of both the cars is

So the vector form is :

Therefore the momentum after the accident is

According to the law of conservation of momentum, we know

From,

We get,

Therefore the speed of Tesla car before collision = 25.4 m/s

The speed of ford car before collision = 24.4 m/s

an obstruction

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.