Answer:
If the system consists of the block only, the work done by the gravity is negative.
If the system consists of the block and the earth the work done by the gravity is zero.
Explanation:
If the system consists of the block only, then the system experiences two external forces: one exerted by the hand that lifts the block vertically upward and other exerted by the earth (gravity), which is opposed to the movement of the system, so the work done by gravity is negative.
On the other hand, if the system consists of the block and the earth, then only exists a external force which is the exerted by the hand. So, the force exerted by gravity is zero.
The If a car is going round a curve , there is an acceleration because the direction of the velocity changes.
<h3>What is the direction of the velocity?</h3>
Now we know that if you throw the ball upwards, the motion is in opposite direction to gravity thus the ball is experiencing deceleration and the speed decreases. The velocity decreases and the acceleration is negative.
If the ball is coming down, then the ball is accelerated thus it speeds up and the direction of the acceleration is positive.
If a car is going round a curve, the vehicle is accelerating because the direction of the velocity changes even if its amount remains constant.
When a board is moving down a hill at 2 ms-1, it is experiencing an acceleration because the motion is in the same direction as gravity.
If a car is coming to a stop at a point, it experiences a deceleration and not an acceleration since the change of velocity with time is negative as the car comes to rest.
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The magnitude of the sum of the frictional forces acting on the bike and its rider is 400N.
<h3>What is friction force?</h3>
The friction force is the opposing force which acts on the object which is in relative motion.
The driving force is equal and opposite to the friction force acting between road and bicycle.
Friction force = 400N
The friction force between rider and bike is zero.
So the magnitude of sum of friction force = 400N +0 = 400N
Thus, the magnitude of the sum of the frictional forces acting on the bike and its rider.
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Answer:
The two methods will yield different results as one is subject to experimental errors that us the Archimedes method of measurement, the the density measurement method will be more accurate
Explanation:
This is because the density method using the calculated volume will huve room for less errors that's occur in practical method i.e Archimedes method due to human error
