(a) For the work-energy theorem, the work done to lift the can of paint is equal to the gravitational potential energy gained by it, therefore it is equal to
where m=3.4 kg is the mass of the can, g=9.81 m/s^2 is the gravitational acceleration and 
is the variation of height. Substituting the numbers into the formula, we find
(b) In this case, the work done is zero. In fact, we know from its definition that the work done on an object is equal to the product between the force applied F and the displacement:
However, in this case there is no displacement, so d=0 and W=0, therefore the work done to hold the can stationary is zero.
(c) In this case, the work done is negative, because the work to lower the can back to the ground is done by the force of gravity, which pushes downward. Its value is given by the same formula used in part (a):
The speed of the cart after 3 seconds of Low fan speed is equal to 54 cm/s.
<h3>How to calculate the speed?</h3>
Mathematically, speed can be calculated by using this formula;
Speed = distance/time
At Low fan speed after 3 seconds, the distance covered is 162 cm:
Speed = 162/3
Speed = 54 cm/s.
At Medium fan speed after 5 seconds, the distance covered is 600 cm:
Speed = 600/5
Speed = 120 cm/s.
At High fan speed after 2 seconds, the distance covered is 128 cm:
Speed = 128/2
Speed = 64 cm/s.
Read more on speed here: brainly.com/question/17350470
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2e min :)) pls park braliest
Answer:
Explanation:
Given
mas of car=870 kg
coffee mug mass=0.47 kg
coefficient of static friction between mug and roof 
Coefficient of kinetic Friction 
maximum car acceleration is 
here coefficient of static friction comes in to action because mug is placed over car . If mug is moving relative to car then \mu _k is come into effect
Answer:
Explanation:
When a body is held against a vertical wall , to keep them in balanced position , normal force is applied on their surface . this force creates normal reaction which acts against the normal force and it is equal to the normal force as per newton's third law . Ultimately friction force is created which is proportional to normal force and it acts in vertically upward direction . It prevents the body from falling down .
Hence normal force = reaction force .
From second law also net force is zero , so if normal force is N and reaction force is R
R - N = mass x acceleration = mass x 0 = 0
R = N .
Ranking normal force from highest to smallest
150 N , 130 N , 120 N
B )
Frictional force is equal to the weight of the body because the body is held at rest .
Ranking of frictional force form largest to smallest
7 kg , 5 kg , 3 kg , 1 kg .
Here frictional force is irrespective of the normal force acting on the body because frictional force adjusts itself so that it becomes equal to weight in all cases here because it always balances the weight of the body .
