Answer:
2.45 J
Explanation:
The following data were obtained from the question:
Mass (m) = 0.5 kg
Height (h) = 1 m
Kinetic energy (KE) =?
Next, we shall determine the velocity of the rock after it has fallen half way. This can be obtained as follow:
Initial velocity (u) = 0 m/s
Acceleration due to gravity (g) = 9.8 m/s²
Height (h) = 1/2 = 0.5 m
Final velocity (v) =?
v² = u² + 2gh
v² = 0² + (2 × 9.8 × 0.5)
v² = 9.8
Take the square root of both side
v = √9.8
v = 3.13 m/s
Finally, we shall determine the kinetic energy of the rock after it has fallen half way. This can be obtained as follow:
Mass (m) = 0.5 kg
Velocity (v) = 3.13 m/s
Kinetic energy (KE) =?
KE = ½mv²
KE = ½ × 0.5 × 3.13²
KE = 0.25 × 9.8
KE = 2.45 J
Therefore, the kinetic energy of the rock after it has fallen half way is 2.45 J
<h3>2
Answers:</h3>
a) Velocity is a vector quantity
e) Velocity is a speed with direction
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Explanation:
If we know the velocity of an object, then we know how fast it's going (speed) and where it's going (direction). It is a vector because the direction of the vector determines the direction, and the length of the vector (aka magnitude) determines the speed. So in a sense we've built in two facts of data into one visual.
An example of velocity: 10 miles per hour north. Here we have the speed of 10 mph and the direction north.
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Extra info:
- Choice B contradicts choice A, so we can cross choice B off the list.
- Choice C is false because speed is a scalar, or single quantity, and not a vector. As mentioned earlier, speed is a part of velocity, but they aren't the same exact thing.
- Choice D is false because the velocity does not account for net force. We don't have any force information built into the velocity.
At the highest point of motion the ball comes to rest momentarily,but it is being pulled down due to the effect of gravity,so its net acceleration is downwards. So,just after that point,it starts falling downwards.
Acceleration is given by:
where
v is the final velocity
u is the initial velocity
t is the time interval
Let's apply the formula to the different parts of the problem:
A) 
Let's convert the quantities into SI units first:
t = 4.0 min = 240 s
So the acceleration is
B) 
As before, let's convert the quantities into SI units first:
t = 94 s
So the acceleration is
C) 
For this part we have to use a different formula:
where we have
v = 0 is the final velocity
u = 89.2 m/s is the initial velocity
a is the acceleration
d = 75 m is the distance covered
Solving for a, we find
