FREE SIFT Mechanical Comprehension Questions and Answers
Danny, a young man from the Northern Hemisphere, is positioned on a scale. Danny is 20 kg heavy. In Newtons, the scale readout is shown. What is Danny's readout?
Explanation:
To convert from kilograms to newtons, we can use the following conversion:
1 kilogram = 9.81 newtons
Therefore, to find their weight of Danny in newtons, we can multiply his weight in kilograms (20 kg) by the conversion factor:
Weight in newtons = 20 kg × 9.81 newtons/kg
Weight in newtons = 196.2 newtons
So the readout for Danny on the weighing scale would be 196.2 N.
2 m are raised by a 50 N vase. What work is completed?
Explanation:
The work done on an object is equal to the force applied to the object multiplied by the distance the object moves in the direction of the force. In this case, a force of 50 N is applied to the vase and it moves a distance of 2 m in the upward direction. So, the work done on the vase can be calculated as:
Work done = force × distance
Work done = 50 N × 2 m
Work done = 100 J
Therefore, the work done on the vase is 100 joules.
An inclined plane's strength increases as its
Explanation:
Increasing the slant of an inclined plane increases its mechanical advantage. The mechanical advantage of an inclined plane is defined as the ratio of the length of the inclined plane to its height. As the slant of the inclined plane increases (i.e., the angle of the incline becomes steeper), the height of the inclined plane decreases, while the length remains the same. This means that the mechanical advantage of the inclined plane increases.
The sliding coefficient of friction for a brick is 0.28. The book must be forced to slide at a constant speed with a force of 5.5 N. What is the brick's mass?
Explanation:
The force required to overcome the frictional force between two surfaces in contact is given by the product of the coefficient of friction and the normal force acting between them. In this case, the brick is being pushed with a force of 5.5 N to overcome the frictional force between it and the surface it is resting on. So, we can use the formula for frictional force to calculate the normal force acting on the brick:
Frictional force = coefficient of friction × normal force
5.5 N = 0.28 × normal force
Normal force = 5.5 N / 0.28
Normal force = 19.64 N
Now, we know that the weight of an object is equal to its mass multiplied by the acceleration due to gravity (9.8 m/s^2). So, we can calculate the weight of the brick as:
Weight of brick = mass of brick × acceleration due to gravity
19.64 N = mass of brick × 9.8 m/s^2
mass of brick = 19.64 N / 9.8 m/s^2
mass of brick = 2.0 kg (rounded to one decimal place)
Therefore, the mass of the brick is approximately 2.0 kg.
A basic machine always has
Explanation:
A simple machine may have less than 100% efficiency due to various factors such as friction between the machine and its surroundings, air resistance, and other losses. Some energy is always lost in the form of heat or sound during the operation of a simple machine, resulting in a decrease in its efficiency. This means that the output work of a simple machine is always less than the input work, resulting in an efficiency of less than 100%.
Christian takes thirty steps forward, followed by thirty steps backward. In terms of his total distance, how many steps has Christian taken?
Explanation:
If Christian walks forward 30 steps and then walks 30 steps backward, he ends up back where he started. Therefore, the total distance he has traveled is equal to the distance he covered while walking forward (30 steps) plus the distance he covered while walking backward (another 30 steps), which gives a total of:
30 steps + 30 steps = 60 steps
So Christian has traveled a total of 60 steps in terms of distance. However, if we consider the displacement (change in position) instead of distance, we see that his net displacement is zero since he ends up back where he started.
The mechanical advantage of a lever with 250 N of resistance and 50 N of effort is
Explanation:
The mechanical advantage (MA) of a lever is defined as the ratio of the resistance force to the effort force, and it gives us an idea of how much the lever can amplify the effort force. So, we can use the given values of resistance force and effort force to calculate the mechanical advantage of the lever.
MA = resistance force/effort force
In this case, the resistance force is given as 250 N and the effort force is given as 50 N.
So, the mechanical advantage of the lever is:
MA = 250 N / 50 N = 5
Therefore, the mechanical advantage of the lever is 5.