Question

What is the acceleration of a ball traveling horizontally with an initial velocity of 20 meters/second and, 2.0 seconds later, a velocity of 30 meters/second?
A. 1.6 meters/second2
B. 3.0 meters/second2
C. 3.4 meters/second2
D. 5.0 meters/second2

Answer 1

Answer: d. 5 m/s^2

Explanation:

Acceleration is the change in velocity in a given time.

a = (30-20)/2 = 5

Answer 2

The ball is travelling in horizontal direction with an acceleration of $\bold{5\ m/ s^{2}}$

Answer: Option D

Explanation:

The rate at which velocity of an object changes is acceleration i.e., if the velocity of an object is changing, the object is accelerating. The unit of measurement of acceleration is Meter per Seconds Square. Acceleration is the derivative of the changing velocity wrt to time,

$a=\frac{\Delta v}{\Delta t}-----{Eqn} 1$

Given,  

Initial velocity = 20 m/s $(v_{i})$  

Final velocity = 30 m/s $(v_{f})$

Initial time = 0 s $(t_{i})$

Final time = 2 s $(t_{f})$

From the equation 1,

$\begin{aligned} a &=\frac{\Delta v}{\Delta t}=\frac{v_{f}-v_{i}}{t_{f}-t_{i}} \\ a &=\frac{30 \mathrm{m} / \mathrm{s}-20 \mathrm{m} / \mathrm{s}}{2 \mathrm{s}}=5 \mathrm{m} / \mathrm{s}^{2} \end{aligned}$

Hence, the acceleration of ball moving horizontally is $\bold{5\ m/s^{2}}$