[tex]\large \mathfrak{Solution : }[/tex]
9. An object which is in circular motion (moving along a circle) is said to be accelerating because it changes it's direction constantly even if it is moving with a constant speed. cuz acceleration is change in either magnitude or direction of an object with respect to time.
therefore, it's still acceleration as change in direction with time.
10. Average speed of an object can be calculated by dividing the total distance covered by an object by time taken to cover that distance.
i.e
- [tex] \boxed{speed = \dfrac{distance}{time} }[/tex]
it can be re- arranged to find the distance as :
- [tex] \boxed{distance = speed \times time}[/tex]
- [tex]time = \dfrac{distance}{speed} [/tex]
11. speed = 20 m/s : conversion into km/h
distance covered : 4 km = 4000 m
- [tex]time = \dfrac{distance}{speed} [/tex]
- [tex]t = \dfrac{4000}{20} [/tex]
- [tex]t = 200 \: \: sec[/tex]
time taken = 200 seconds
12. let's use the first equation of motion to find the acceleration :
- [tex]50 = 80 + 120a[/tex]
- [tex]50 - 80 = 120a[/tex]
- [tex]a = \dfrac{ - 30}{120} [/tex]
- [tex]a = - \dfrac{1}{4} m/s {}^{2} [/tex]
- [tex] - 0.25 \: \: m/s {}^{2} [/tex]
