The speed of the tennis ball is 8 km/h when Alana throws the ball behind at the speed of 11 km/h.
<h3>What is the
frame of
reference?</h3>
It is a point from where the motion is observed. The speed changes with the frame of reference.
For the person standstill on the sidewalk, If Alana throw the ball in the front direction, The speed will be,
19+11 = 30 km/h
It Alana just leave the ball, the speed,
19 +0 = 19 km/h
If Alana throws the ball behind her at the speed of 19 km/h. The speed of the ball for a sidewalk observer,
19 +(-19 ) = 0 km/h
Thus, when Aana throw the ball behind the velocity will be negative,
So,
19 + (-11 ) = 8 km/h
Therefore, the speed of the tennis ball is 8 km/h when Alana throws the ball behind at the speed of 11 km/h.
Learn more about Frame of reference:
brainly.com/question/9820962
Answer: 2 m/s^2
Explain
£F=ma
net force = mass x acceleration
4N is a force acting on it
4N=(2kg) a
2kg is the mass
you divide the 2 over
and A= 2 m/s^2
Answer:
See the explanation below
Explanation:
We must solve this problem by defining that when we have a constant velocity, the acceleration is equal to zero. That is, when there is no speed change, there is no acceleration. We can understand it very easily by means of the following equation of kinematics.
where:
Vf = final velocity = 55 [km/h]
Vo = initial velocity = 55 [km/h]
a = acceleration [m/s²]
t = time [s]
As we can see there is no change in speed, and the difference between the two is equal to zero.
