# Calculating the Force of a Kangaroo's Legs

• Shoebox
In summary, the kangaroo's legs are able to exert a force of 1881 Newtons on the ground to jump a height of 1 meter.
Shoebox
Member warned about misplacing homework questions in technical forum sections
Kangaroos have large, powerful legs for jumping. A male kangaroo that has a mass of 66.5 kg can accelerate to a vertical velocity of 6.08 before his feet leave the ground (at a height of 1m). What force is the kangaroo's legs able to exert on the ground in order to do this?

Assuming that the height is 0 initially,

6.08^2 = 2a
F = 66,5 (a + 9,81)

You have the final velocity and also the distance covered before attaining that velocity, so use 3rd equation of motion and find acceleration, i think you can do the rest!

thank you! my only question is, how did you know this part: 6.08^2=2a?

v²-u²=2as and your u=0 and s=1

Timeless velocity equation: v(final)^2 = 2ax if there is uniform acceleration. It is easy to derive from a simple velocity vs. time graph.

and now to figure out how high he can jump. I am not sure what to use, because f=ma does not deal with distance

Use the same formula.

the formula for the previous is the same as vf^2=vi^2+2ax, correct?

Shoebox said:
f=ma
You know both the quantities on the RHS.

Shoebox said:
the formula for the previous is the same as vf^2=vi^2+2ax, correct?
yes

okay.. 6.08^2=2(18.48)(x)
im getting x=1..where am i going wrong?

No, you found ## a## from the equation v²=2ax... ;you already know## x=1 m## you should find ##a## , which you have done very nicely,now substitute in the formula ##F=ma##

i found the force to be 1881. Now i am trying to find how far he can jump, or x

For that you need to use a=g and vintial= 6.08 units, because the kangaroo is in the air and gravity is acting on it.
substitute in the equation##v²_{final}-v²_{initial}=2ax## be careful while you choose the sign for ##a## when you substitute.

so my equation setup would be:
(0)^2 - (6.08)^2=2(18.48)(x)

Shoebox said:
how far he can jump, or x
how far, or how high??

high

Shoebox said:
so my equation setup would be:
(0)^2 - (6.08)^2=2(18.48)(x)
choose your## a## well, its in the air, gravity acts on it so it should be ##a=g=-9.8 m/s²## can you tell me why the -ve sign?

thats right, gravity acts on him once he jumps. okay i solved (0)^2 - (6.08)^2=2(9.8)(x) and got x=1.886

the -9.8 is negative because of the direction of his acceleration.

Good, but i don't see you use it here
Shoebox said:
. okay i solved (0)^2 - (6.08)^2=2(9.8)(x) and got x=1.886

## 1. How strong are a kangaroo's legs?

A kangaroo's legs are incredibly powerful and can produce a force of up to 850 pounds per square inch, which is equivalent to the force of a small car.

## 2. How is the force of a kangaroo's legs calculated?

The force of a kangaroo's legs can be calculated by using the formula F = m x a, where F is force, m is mass, and a is acceleration. By measuring the mass of the kangaroo and the acceleration of its legs, the force can be determined.

## 3. What makes a kangaroo's legs so strong?

Kangaroo's legs are strong due to a combination of their muscular structure and unique anatomy. They have long tendons and elastic ligaments that store energy, allowing them to generate powerful jumps and kicks.

## 4. How does a kangaroo's leg strength compare to other animals?

Kangaroos have some of the strongest legs in the animal kingdom. They are surpassed only by animals such as elephants, rhinos, and horses, which are much larger in size.

## 5. Can the force of a kangaroo's legs be dangerous?

Yes, the force of a kangaroo's legs can be dangerous. They are known to use their legs to defend themselves against predators and can cause serious injury with their powerful kicks. It is important to always observe kangaroos from a safe distance to avoid any potential danger.

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