Find the relativistic momentum of a proton moving at speed 0.96c. (a proton has

The
the general formula of the relativistic momentum is given by p, such that 

p=  gamma x mo x V, 
where:  v= the speed of a the moving material point.(proton in our case)
             mo=the initial mass of the proton=1.673 × 10–27 kg           
 and 

gamma = 1 / sqrt(1- V² / C²), where C is the speed of the light, it is equal to 3.10^5 km/s

so gamma= 1/ sqrt(1- V² / C²)=1/ sqrt(1- 0.96²C² / C²)=1/ sqrt(1- 0.96²)=1/ sqrt(1- 0.96²)=1/ sqrt(1- 0.92)=1/ sqrt(0.08)=3.53

therefore, p=  gamma x mo x V=3.53 xmox0.96C= 3.53 x1.673 × 10–27x 0.96 x 3x10^5=1.697 x 10^-21

finally  p= 1.697 x 10^-21

For this problem, you should use Pythagorean Theorem.

The formula for this is a^2 + b^2 = c^2.

The plane is moving north, and then moves to the right. Therefore, we need to find the hypotenuse, or resultant velocity. Plugging it into the equation we get, (245 m/s)^2 + (55 m/s)^2 = c^2

Solving for this, you will get 250 m/s.