Answer:
(a)

(b)
1120 N
Explanation:
Change in velocity,
is given by subtracting the initial velocity from the final velocity and expressed as 
Where v represent the velocity and subscripts f and i represent final and initial respectively. Since the ball finally comes to rest, its final velocity is zero. Substituting 0 for final velocity and the given figure of 8 m/s for initial velocity then the change in velocity is given by

To find
then we substitute 7 kg for m and -8 m/s for
therefore 
(b)
The impact force, F is given as the product of mass and acceleration. Here, acceleration is given by dividing the change in velocity by time ie

Substituting t with 0.05 s then 
Since F=ma then substituting m with 7 Kg we get that F=7*-160=-1120 N
Therefore, the impact force is equivalent to 1120 N
Explanation:
First convert the speed into m/s and time into seconds
Answer:
She covers the distance is 12 km.
The magnitude of displacement is 8.6 km.
The direction of her displacement is north east.
Explanation:
Given that,
Christina drives his moped 7 kilometers North and stop for lunch and then drive 5 km east.
We need to calculate the total distance
Using formula of distance

Put the value into the formula


We need to calculate the magnitude of displacement
Using formula of displacement




The direction of her displacement is north east.
Hence, She covers the distance is 12 km.
The magnitude of displacement is 8.6 km.
The direction of her displacement is north east.
A good scientific question has certain characteristics. It should have some answers (real answers), should be testable (can be tested by someone through an experiment or measurements), leads to a hypothesis that is falsifiable (means it should generate a hypothesis that can be shown to fail), etc.