Answer:
The breaking in <em>molecular</em> bonds in food releases energy for your body to use.
The correct answer is
Air resistance
In fact, when a ball is in free fall, there are two forces acting on it:
- its weight (force of gravity), acting downward
- the air resistance, acting upward
The effect of the weight is to accelerate the ball, because its direction is the same as the direction of motion of the ball, while the effect of the air resistance is to slow down the ball, because its direction is opposite to that of the motion.
Answer:
Less friction
Explanation:
Paolo's bike is too difficult to pedal because there is too much friction in the mechanisms of the bike. To reduce friction, Paolo must oil the chain. This will make the bike run much more smoothly and allow for easier pedalling.
Answer:
<em>v = 381 m/s</em>
Explanation:
<u>Linear Speed</u>
The linear speed of the bullet is calculated by the formula:
Where:
x = Distance traveled
t = Time needed to travel x
We are given the distance the bullet travels x=61 cm = 0.61 m. We need to determine the time the bullet took to make the holes between the two disks.
The formula for the angular speed of a rotating object is:
Where θ is the angular displacement and t is the time. Solving for t:
The angular displacement is θ=14°. Converting to radians:
The angular speed is w=1436 rev/min. Converting to rad/s:
Thus the time is:
t = 0.0016 s
Thus the speed of the bullet is:
v = 381 m/s
<span>A physical change is any change that alters the form or appearance of a substance but does not change it into another substance
-Some of the physical properties may be altered, but the chemical composition stays the same
-Examples: Bending, Crushing, Cutting, Melting, Freezing, Boiling</span>
