Answer:
<em>Answer: B. 49 N</em>
Explanation:
<u>Friction Force
</u>
When an object is at rest on a rough surface, it encounters a friction force that opposes motion.
The friction force when an object is moving on a horizontal surface is calculated by:

Where
is the coefficient of static friction and N is the normal force.
If no forces other then the weight and the normal are acting upon the y-direction, then the weight and the normal are equal in magnitude:
N = W = m.g
Thus, the friction force is:
We are given the coefficient of static friction
and the mass of the object m=10 Kg. The minimum force needed to make it start moving is the maximum friction force:
Fr=0.5*10*9.8
Fr = 49 N
Answer: B. 49 N
<h2>Answer:</h2>
<u>The correct answer is </u><u>(A) The chemical energy in the food is converted to mechanical energy to give the body energy to move.
</u>
<h2>Explanation:</h2>
The chemical energy in food can be converted to another form of chemical energy when it is stored as glucose or fat. The chemical energy in our food can also be converted to mechanical energy in the form of muscle movement and it provides us energy to travel and move from one place to another pace. The entire energy is not converted to mechanical though, it is also converted into heat energy.
Answer:
The theory of Relativity state that :<u>Special relativity applies to all physical phenomena in the absence of gravity and General relativity explains the law of gravitation and its relation to other forces of nature. </u>
C. The canoe's path will be a diagonal line from northeast to southwest.
Explanation:
We can solve this problem by using vector addition rules.
In fact, we know that:
- The velocity of the canoe has a component in the south direction, due to the velocity of the river which points towards south
- The canoe itself is trying to go from the eastern shore towards the western shore --> this means that the canoe has also a component of the velocity in the west direction
This means that the resultant velocity of the canoe must be in a direction intermediate between the directions of its two components: therefore, in the southwest direction.
Therefore, this means that
C. The canoe's path will be a diagonal line from northeast to southwest.
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The work done by the force in pulling the block all the way to the top of the ramp is 3.486 kJ.
<h3>What is work done?</h3>
Work done is equal to product of force applied and distance moved.
Work = Force x Distance
Given is a block with a weight of 620 N is pulled up at a constant speed on a very smooth ramp by a constant force. The angle of the ramp with respect to the horizontal is θ = 23.5° and the length of the ramp is l = 14.1 m.
From the Newton's law of motion,
ma =F-mg sinθ =0
So, the force F = mg sinθ
Plug the values, we get
F = 620N x sin 23.5°
F = 247.224 N
Work done by motor is W= F x d
The force is equal to the weight F = mg
So, W = 247.224 x 14.1
W = 3.486 kJ
Thus, the work done by the force in pulling the block all the way to the top of the ramp is 3.486 kJ.
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