Answer:
1000 N
Explanation:
First, we need to find the deceleration of the running back, which is given by:

where
v = 0 is his final velocity
u = 5 m/s is his initial velocity
t = 0.5 s is the time taken
Substituting, we have

And now we can calculate the force exerted on the running back, by using Newton's second law:

so, the magnitude of the force is 1000 N.
Answer:
Muscle contraction thus results from an interaction between the actin and myosin filaments that generates their movement relative to one another. The molecular basis for this interaction is the binding of myosin to actin filaments, allowing myosin to function as a motor that drives filament sliding.
The correct answer for the question that is being presented above is this one: "B.pushing against a car without moving it." According to the scientific definition, pushing against a car without moving it is not an example of work. Lifting a book off a desk and <span>pulling socks out of the drye are samples of work.</span>
Here stress is parallel to the surface of the body. So it's a Shear stress.
The given data is incomplete. The complete question is as follows.
At an accident scene on a level road, investigators measure a car's skid mark to be 84 m long. It was a rainy day and the coefficient of friction was estimated to be 0.36. Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes. (why does the car's mass not matter?)
Explanation:
Let us assume that v is the final velocity and u is the initial velocity of the car. Let s be the skid marks and
be the friction coefficient and m be the mass of car.
Hence, the given data is as follows.
v = 0, s = 84 m,
= 0.36
According to Newton's law of second motion the expression for acceleration is as follows.
F = ma
= ma
= ma
a = 
Also,



= 
= 24.36 m/s
Thus, we can conclude that the speed of the car when the driver slammed on (and locked) the brakes is 24.36 m/s.