A) 3 m/s² B) 7 m/s² C) 10 m/s² D) 15 m/s²
______
2. A runner accelerates from rest at a rate of 2 m/s². How fast is he running at the
end of 5 seconds?
A) 4 m/s B) 6 m/s C) 10 m/s D) 16 m/s
______
3. An object is in a free fall. Which of the following forces is affecting its flight as the
object falls?
A) air resistance B) gravity C) wind D) the hand that threw it
______
4. A baseball pitcher throws a fastball at 30 meters per second. If the batter is 15
meters from the pitcher, approximately how much time does it take for the ball to
reach the batter?
A) 450 s B) 0.25 s C) 0.5 s D) 3 s
______
5. The average speed of a plane was 600 kilometers per hour. How long did it take
the plane to travel 1200 kilometers?
A) 0.7 hour B) 5 hour C) 0.5 hour D) 2 hour
______
6. The average speed of a runner in a 400-meter race is 10.0 meters per second.
How long did it take the runner to complete the race?
A) 40 sec B) 50 sec C) 32 sec D) 80 sec
______
7. The prefix that has a value of 10^-6 is
a) milli b) kilo c) mega d) micro
I don't understand these… Thanks ahead of time!
1. Acceleration = Final Velocity – Initial Velocity / Time
a = v-u/t a=55-5/5 a =50/5 a = 10m/s^2 = C
2. Same equation as above a = v-u/t but rearranged to find V.
2 = v-0/5 2 = v/5 v = 10m/s = C
3. An object in free fall only has gravity affecting it = B
4. Distance = Speed x Time.
time = 15/30 = 0.5s = C
5. Same equation as above.
1200/600 = 2 hours = D
6. D=ST, T=400/10 = 40s = A
7. Micro = D
{ 1 comment… read it below or add one }
I'll show you how to answer the first one intuitively. This usually helps if you forget the equation for solving this (which, by the way is a = (final velocity – original velocity) / time). The whole thing lasts for five seconds, and the car accelerates from 5 m/s to 55 m/s. An acceleration means that the object increases or decreases its speed every second at a constant rate. For example, if my acceleration is 10 m/s^2, this means I am going 10 m/s faster every second. In 2 seconds, I am going 20 m/s. In 3 seconds, I am going 30 m/s. Just use the answers and you'll find that 10 m/s^2 is the right answer: add 10 m/s to the original velocity for the 5 seconds the problem lasts, and you get 55 m/s. Hope this isn't confusing! Just use the equation I previously put if this method is confusing.
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