A old Chevy accelerates at a rate of 3.8 m/s^2. How much time would it take to reach the speed limit of 100 km if the car was travelling at the speed of 70.0 km?
a) 2.9 s
b) 3.7 s <----
c) 5.4 s
d) 30.0 s
2. Find the acceleration of a skier sliding down a mountain at a rate of 32.0 m/s for 10.0 s.
Answer: a = -3.2 m/s^2
I hope the speed is km/s
You will have to convert km/s to m/s
Acceleration=change in velocity/time
Change in velocity/acceleration=time
So,
100km/s -70km/s/3.8m/s=t
t= about 8 s; I don't agree with any of these answers.
2.)
You are correct.
Sorry! The speed is 110 km/h! So sorry! D:
Then the answer should be answer choice A, and not B.
Acceleration=change in velocity/time
Change in velocity/acceleration=time
So,
110km/h=30.56m/s
and
70km/h=19.44m/s
(30.56m/s-19.44m/s)/3.8m/s=t
t=11.12m/s/3.8m/s
t=2.9s
Thanks! One question: Do I have to convert km/h to m/s at the beginning? Will I get the same answer if I convert at the end?
Doesn't matter when you convert it, but the units have to be the same once you perform the calculations. Conversely, you could have just converted the acceleration from m/s to km/h. I thought it was easier to do by converting the velocity.
Best.
To answer the first question, we need to use the equation for calculating time using acceleration and change in speed. The equation is:
time = (final speed - initial speed) / acceleration
Given:
Initial speed (u) = 70.0 km/h = 70.0 km/h * (1000 m / 1 km) * (1 h / 3600 s) = 19.4 m/s
Acceleration (a) = 3.8 m/s^2
Final speed (v) = 100 km/h = 100 km/h * (1000 m / 1 km) * (1 h / 3600 s) = 27.8 m/s
Substituting the values into the equation, we get:
time = (27.8 m/s - 19.4 m/s) / 3.8 m/s^2 = 2.17 s
Since the given answer choices are in seconds, we need to round our answer to the nearest second. Now, let's analyze the given answer choices:
a) 2.9 s
b) 3.7 s <---- This is the correct answer, based on the calculation above.
c) 5.4 s
d) 30.0 s
Therefore, the correct answer is b) 3.7 s.
Moving on to the second question, we are given the initial speed of a skier (32.0 m/s) and the time duration (10.0 s). To find the acceleration, we need to use the equation:
acceleration = (final speed - initial speed) / time
Given:
Initial speed (u) = 32.0 m/s
Time (t) = 10.0 s
Since the skier is sliding down the mountain, we can assume the final speed is 0 m/s (as the skier comes to a stop).
Substituting the values into the equation, we get:
acceleration = (0 m/s - 32.0 m/s) / 10.0 s = -3.2 m/s^2
Therefore, the acceleration of the skier sliding down the mountain is -3.2 m/s^2.