<h2>
Answer:50
</h2>
Explanation:
Let
be the airspeed.
Let
be the cross wind speed.
We know that,ground speed is the vector sum of airspeed and cross wind speed and airspeed is perpendicular to cross wind speed.
If
and
are two perpendicular vectors,the resultant vector has the magnitude 
Given,

So,the ground speed is 
Explanation:
<em><u>Principle of Floatation</u></em>
Principle of Floatation states that weight of floating body is equal to weight of water displaced by it
Answer:
He needs 1.53 seconds to stop the car.
Explanation:
Let the mass of the car is 1500 kg
Speed of the car, v = 20.5 m/s
He will not push the car with a force greater than, 
The impulse delivered to the object is given by the change in momentum as :

So, he needs 1.53 seconds to stop the car. Hence, this is the required solution.
Answer:
The value is
Explanation:
From the question we are told that
The mass of the car is
The acceleration is 
Generally the net force applied on the rope is mathematically represented as

Here W is the weight of the car which is evaluated as
=> 
=> 
Generally the net force can also be mathematically represented as
So

=> 
=>