# Calculate: Block's Kinetic Energy, Work by Forces, & Gravity

• Sportsman4920
In summary, the conversation discusses the calculation of various types of work done on a 5.4 kg block being pushed up a rough inclined plane by a 75 N force. The initial kinetic energy of the block is calculated using the formula KE = 1/2mv^2, where m is the mass of the block and v is its initial velocity. The work done by the 75 N force can be calculated using the formula W = Fd cos(theta), where F is the force, d is the distance, and theta is the angle between them. Similarly, the work done by the friction force can be calculated using the same formula. The work done by gravity can be calculated using the formula W = mgh, where m
Sportsman4920
A 5.4 kg block is pushed 3.0 m up a rough 37° inclined plane by a horizontal force of 75 N. If the initial speed of the block is 2.2 m/s up the plane and a constant kinetic friction force of 25 N opposes the motion, *calculate the following.
(a) the initial kinetic energy of the block
J
(b) the work done by the 75 N force
J
(c) the work done by the friction force
J
(d) the work done by gravity
J
(e) the work done by the normal force
J
(f) the final kinetic energy of the block
J

what have u done to answer them yourself?

$$W = |F||D|cos\theta$$ theta being the angle between force and displacement vectors. That should take care of the first 5. The last one looks like $$W_{net} = \Delta KE$$

Last edited:
thank you

I tried to use the formula but I can't get the right answer.

how would you do part be on this question?

In part B the force is 75N the distance is 3m and the angle between them is 37 degrees, so using the formula the work should be 180 N*m

Thanks, now I'm trying to find the work done by friction. so I did W=25N*5.2(distance)*cos(theta but it didn't work

## 1. What is kinetic energy?

Kinetic energy is the energy that an object possesses due to its motion. It is calculated by multiplying the mass of the object by the square of its velocity and dividing by 2.

## 2. How do you calculate the kinetic energy of a block?

The kinetic energy of a block can be calculated by using the formula: KE = 1/2 * m * v^2, where KE is the kinetic energy, m is the mass of the block, and v is the velocity of the block.

## 3. What is work done by forces?

Work done by forces is the amount of energy transferred to an object by a force acting on it. It is calculated by multiplying the magnitude of the force by the displacement of the object in the direction of the force.

## 4. How is work related to kinetic energy?

According to the work-energy theorem, the work done by all forces acting on an object is equal to the change in kinetic energy of the object. This means that work done by forces can either increase or decrease the kinetic energy of an object.

## 5. What is the role of gravity in calculating kinetic energy and work done by forces?

Gravity is a force that can do work on an object and therefore, plays a role in the calculation of kinetic energy and work done by forces. When an object is moving against the force of gravity, it has to do work to overcome it, which increases its kinetic energy. On the other hand, if an object is moving with the force of gravity, the force does work on the object, decreasing its kinetic energy.

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