Answer:
(a) - 42700 m/s 
(b) - 6.8 x 10^-4 m/s^2
Explanation:
initial velocity of star, u = 20.7 km/s 
Final velocity of star, v = - 22 km/s 
time, t = 1.99 years 
Convert velocities into m/s and time into second 
So, u = 20700 m / s 
v = - 22000 m/s
t = 1.99 x 365.25 x 24 x 3600 = 62799624 second
(a) Change in planet's velocity = final velocity - initial velocity 
   = - 22000 - 20700 = - 42700 m/s
(b) Accelerate is defined as the rate of change of velocity.
Acceleration = change in velocity / time 
                      = ( - 42700 ) / (62799624) = - 6.8 x 10^-4 m/s^2
 
        
             
        
        
        
Answer:
Gamma rays are mostly used in the radiotherapy/ radiooncology to treat cancer. They can also be used to spot tumours. Gamma rays can kill living cells and damage malignant tumor
 
        
             
        
        
        
Answer:
c large, spherical body that orbits in a clear path around a star
Explanation:
you can not say b because the sun is a star and you cant say a and d because all planets are not made of rock and all planets are not made of gas
 
        
             
        
        
        
Explanation :
The full form of laser is Light Amplification by Stimulated Emission of Radiation. It has particles of very high energy. It points in one direction.
Greg is giving a slide show presentation to a large audience. It is very important to make the presentation informative. By using a laser, we can focus on the important part of the presentation. So that we can highlight the important points.