Answer:
This is known as a Galilean transformation where
V' = V - U
Where the primed frame is the Earth frame and the unprimed frame is the frame moving with respect to the moving frame
V - speed of object in the unprimed frame
U - speed of primed frame with respect to the unprimed frame
Here we have:
V = -15 m/s speed of ball in the moving frame (the truck)
U = -20 m/s speed of primed (rest) frame with respect to moving frame
So V' = -15 - (-20) = 5 m/s
It may help if you draw a vector representing the moving frame and then add
a vector representing the speed of the ball in the moving frame.
Acceleration = Change in Velocity / time
a = (v - u) / t
Where v = final velocity in m/s
u = initial velocity in m/s
t = time in seconds.
a = acceleration in m/s²
A proper record of the changes in velocity with the corresponding time would help find the acceleration.
Cocking your head would be most useful for detecting the LOCATION of a sound.
Answer:
1185 N
Explanation:
From Newton’s second law of motion,
F=ma where m= mass of motorcycle, a is acceleration of the motorcycle and F=Force
Net force acting on motorcycle 
is given by 
Where F is force acting on motorcycle and f is frictional force
Substituting F-f for
hence ma= F- f Substituting a with 3, m with 245Kg and f with 450N as provided
245*3= F- 450
F=245*3 +450= 1185 N
