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3 years ago

How much kinetic energy does a 7.2-kg dog need to make a vertical jump of 1.2 m? (The acceleration due to gravity is 9.8 m/s2.)

Physics

2 answers:

V125BC [204]3 years ago

7 0

How much kinetic energy does a 7.2-kg dog need to make a vertical jump of 1.2 m?
Answer:

85 Joule (approx)

Explanation:

Potential energy at highest point

P.E = mgh = 7.2 kg × 9.8 m/s2×1.2 m≈85 Joule

This is the kinetic energy required for dog to jump a height of 1.2 m.

hope this helps!

Tasya [4]3 years ago

6 0

Answer:

Kinetic energy of dog is 84.67 Joules

Explanation:

Given that,

Mass of the dog, m = 7.2 kg

We have to find the kinetic energy does a 7.2-kg dog need to make a vertical jump of 1.2 m. We know that the energy of a system remains conversed. At highest point there is only potential energy. So, while taking a vertical jump the potential energy gets converted to potential energy.

So, $E_k=mgh$

here, h = 1.2 m

$E_k=7.2\times 9.8\times 1.2$

$E_k=84.67\ Joules$

Hence, the kinetic energy needed to make a vertical jump is 84.67 Joules.

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On earth, two parts of a space probe weigh 14500 N and 4800 N. These parts are separated by a center-to-center distance of 18 m

Nastasia [14]

Answer:

$F = 1.489*10^{-7} N$

Explanation: Weight of space probes on earth is given by: $W= m*g$

W= weight of the object( in N)

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Therefore,

$m_{1} = \frac{14500}{9.81}$

$m_{1} = 1478.08 kg$

Similarly,

$m_{2} = \frac{4800}{9.81}$

$m_{2} = 489.29 kg$

Now, considering these two parts as uniform spherical objects

Also, according to Superposition principle, gravitational net force experienced by an object is sum of all individual forces on the object.

Force between these two objects is given by:

$F = \frac{Gm_{1} m_{2}}{R^{2} }$

G= gravitational constant ( $6.67 * 10^{-11} m^{3} kg^{-1} s^{-2}$ )

$m_{1} , m_{2}$ = masses of the object

R= distance between their centres (in m)(18 m)

Substituiting all these values into the above formula

$F = 1.489*10^{-7} N$

This is the magnitude of force experienced by each part in the direction towards the other part, i.e the gravitational force is attractive in nature.

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3 years ago

A train moves from rest to a speed of 25 m/s in 30.0 seconds. What is the acceleration?

fredd [130]

Answer:

$a = 0.83\ m/s^2$