the correct answer is B. 1.27
Mechanical advantage of a lever is simply the ratio of the effort arm to the load arm.Effort arm is the distance from the pivot to the point of application of force while load arm is the distance of the lord from the pivot.
therefore, in this question, the effort arm is 0.28m while the load arm is 0.22 m. MA is calculated as follows: MA=effort arm/load arm
=0.28m/0.22m=1.27
Answer:
Explanation:
(ΔK + ΔUg + ΔUs + ΔEch + ΔEth = W)
ΔK is increase in kinetic energy . As the athelete is lifting the barbell at constant speed change in kinetic energy is zero .
ΔK = 0
ΔUg is change in potential energy . It will be positive as weight is being lifted so its potential energy is increasing .
ΔUg = positive
ΔUs is change in the potential energy of sportsperson . It is zero since there is no change in the height of athlete .
ΔUs = 0
ΔEth is change in the energy of earth . Here earth is doing negative work . It is so because it is exerting force downwards and displacement is upwards . Hence it is doing negative work . Hence
ΔEth = negative .
b )
work done by athlete
= 400 x 2 = 800 J
energy output = 800 J
c )
It is 25% of metabolic energy output of his body
so metalic energy output of body
= 4x 800 J .
3200 J
power = energy output / time
= 3200 / 1.6
= 2000 W .
d )
1 ) Since he is doing same amount of work , his metabolic energy output is same as that in earlier case .
2 ) Since he is doing the same exercise in less time so his power is increased . Hence in the second day his power is more .
F = ma = -kx
a = 9.81 m/s²
k = 3430 N/m
m = 70 kg
x = - ma/ k = 0.2m
Answer:
a) The uniform velocity travelled by the car is 10 meters per second.
(Point b has been erased by the user)
c) The distance travelled by the car with uniform velocity is 100 meters.
Explanation:
a) Calculate the uniform velocity travelled by the car:
The uniform velocity is the final velocity (
), in meters per second, of the the uniform accelerated stage:
(1)
Where:
- Initial velocity, in meters per second.
- Acceleration, in meters per square second.
- Time, in seconds.
If we know that 
, 
and 
, then the uniform velocity is:
The uniform velocity travelled by the car is 10 meters per second.
(Point b has been erased by the user)
c) The distance travelled by the car (
), in meters, with uniform velocity is calculated by the following kinematic expression:
(2)
If we know that and 
, then the distance travelled is:
The distance travelled by the car with uniform velocity is 100 meters.
