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ohaa [14]
3 years ago
9

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees

upon landing to reduce the force of the impact. A 75-kg man just before contact with the ground has a speed of 4.6 m/s. (a) In a stiff-legged landing he comes to a halt in 2.1 ms. Find the average net force that acts on him during this time. N (b) When he bends his knees, he comes to a halt in 0.09 s. Find the average force now. N (c) During the landing, the force of the ground on the man points upward, while the force due to gravity points downward. The average net force acting on the man includes both of these forces. Taking into account the directions of these forces, find the force of the ground on the man in parts (a) and (b). stiff legged landing N bent legged landing

Physics
1 answer:
dolphi86 [110]3 years ago
6 0

Answer:

a) 1.725*10^5 N

b) 3.83*10^3 N

c) i) 173.24 kN

c) ii) 4.57 kN

Explanation:

See the attachment for calculations

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A bike accelerates uniformly(from rest to a speed of 7 m/s over a distance of 40 m. Determine
marshall27 [118]

Answer:

0.61 m/s^2

Explanation:

The bike's acceleration can be found by using the following suvat equation:

v^2-u^2=2as

where

v is the final velocity of the bike

u is the initial velocity

a is the acceleration

s is the distance covered

For the bike in the problem,

u = 0

v = 7 m/s

d = 40 m

Solving the equation for a, we find the acceleration:

a=\frac{v^2-u^2}{2s}=\frac{7^2-0}{2(40)}=0.61 m/s^2

3 0
4 years ago
What is the difference between mass and weight?​
PIT_PIT [208]
Mass: the amount of matter an object contains
Weight: mass•acceleration due to gravity(9.8m/s) / the force of gravity acting on an object
4 0
3 years ago
A student is holding a stone at a certain height. The stone has 50 joules of potential energy and 0 joules of kinetic energy. Th
Hitman42 [59]

Answer:

d) The stone will have about 50 joules of kinetic energy and 0 joules of potential energy​ .

Explanation:

Given :

Initial Potential energy , P_i=50\ J .

Initial Kinetic energy , K_i=0\ J . ( because ball is in rest )

Now , we know , kinetic energy is maximum when an object reaches ground .

Also , potential energy is zero when an object is in ground .

We know , by conservation of energy :

Initial total energy = Final total energy

P_i+K_i=P_f+K_f\\\\50+0=0+K_f\\\\K_f=50 \ J

Therefore , option d) is correct .

6 0
4 years ago
We can calculate the force that the atmospheric pressure produces on a surface. Consider a living room that has a 4.0m×5.0m floo
qaws [65]

Answer:

Force, F=2.02\times 10^6\ N

Explanation:

It is given that,

Length of the room, l = 4 m

breadth of the room, b = 5 m

Height of the room, h = 3 m

Atmospheric pressure, P=1\ atm=101325\ Pa

We know that the force acting per unit area is called pressure exerted. Its formula is given by :

P=\dfrac{F}{A}

F=P\times l\times b

F=101325\times 4\times 5

F=2.02\times 10^6\ N

So, the total force on the floor due to the air above the surface is 2.02\times 10^6\ N. Hence, this is the required solution.

4 0
3 years ago
Two long straight parallel lines of charge, #1 and #2, carry positive charge per unit lengths of λ1 and λ2, respectively. λ1 &gt
Stella [2.4K]

Answer:

Somewhere between the two wires, but closer to the wire carrying λ₂

Explanation:

Electric Field for a point at distance x from an electric charge Q is Ef = K*Q/x².

Electric Fied due to an electric charge is a vector and its direction is  such that  if we place a positive charge in the point it will be rejected ( equal sign charge repulse each other and different attract each other)

According to that previous explanation, it is no possible two have Ef=0 out of the two wires region, since above the upper wire and below the lower wire we have to add the two electric fields (both have the same direction). Therefore we only have possibilities of Ef = 0 inside the two wires, where the repulsion produced over a positive charge due to the two wires  are opposite

In the particular case in which λ₁ and λ₂ are equals then all the points exactly in the middle of d (distance between the two wires ) will have Ef =0.

As we can see at the beginning of the step by step explanation Electric field is proportional to the electric charge, or for a bigger charge, bigger Ef (keeping constant distance). In our case λ₁ >λ₂ then E₁ (Electric field produced by a wire carrying λ₁ will be bigger than (Electric field produced by wire carrying λ₂ at the middle way between the wires.

But for points closer to wire with λ₂  ( where E₂ is bigger than E₁ ) we will surely find an appropriate distance  to get equals E and then Ef = 0

3 0
3 years ago
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