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2 years ago

Describe some basic guidelines for safe PRE

1 answer:

3 0

PRE stands for progressive resistance exercises. This refers to exercises which progressively increase the load applied to the muscles. Here are some guidelines for safe PRE:

1. Do the exercises slowly, surely and smoothly. Avoid doing abrupt movements so as not to strain your muscles.
2. When doing the exercises, make your you execute them properly. For example, when lifting weights, lift them all the way up and all the way down.
3. Use spotters for support and to avoid accidents.

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A 53.0 kg sled is sliding on snow with μk=0.110. how much friction force does it feel?

Anon25 [30]

Answer:

57N

Explanation:

$F_F = \mu F_N = \mu mg = 0.11 \times 53 kg \times 9,8 \frac{m}{s^{2} }$

6 0

2 years ago

Read 2 more answers

Roughly to what height would a 5 kg stone need to be raised in order to have the same stored energy as the energy stored in the

hoa [83]

8.16m is the required height, a 5kg stone need to be raised.

One sort of potential energy is gravitational potential energy, which is equal to the product of the object's mass (m), the gravitational acceleration (g), and the object's height (h) as measured in relation to the ground's surface (the body).

We obtain the formula by considering the work done in raising a mass m through a height h.

Work in elevating mass m through height h is equal to force times distance.

The force must be greater than the mass m's weight, hence F = mg.

Work done = mgh = gravitational potential energy

Energy = Mass of the object × gravitational acceleration × height.

Mass of the stone = 5kg

Equating ;

∴ 400 J = 5 kg × 9.8 m/s² × height

Height = 8.16 m

Therefore, 8.16m is the required height.

Learn more about energy here:

brainly.com/question/1242059

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8 0

2 years ago

If you are trying to loosen a stubborn screw from a piece of wood with a screwdriver and fail, should you find a screwdriver for

dmitriy555 [2]

A fatter handle. This allows you to provide more torque to the screw, which should eventually loosen it.

4 0

3 years ago

Read 2 more answers

A spring with a spring constant of 120 J/m2 is fixed to a wall, free to oscillate. On the other end, a ball with a mass of 1500

Neporo4naja [7]

Answer:

A. 4.47 m/s

Explanation:

As the ball oscillates, it mechanical energy, aka the total kinetic and elastics energy stays the same. For the ball to be at maximum speed, its elastic energy i 0 and vice versa. When the ball is at rest, its kinetic energy is 0 and its elastic energy is at maximum at 50 cm, or 0.5 m

1500 g = 1.5 kg

$E_e = E_k$

$kx^2/2 = mv^2/2$

$120*0.5^2/2 = 1.5*v^2/2$

$15 = 0.75v^2$

$v^2 = 15 / 0.75 = 20$

$v = \sqrt{20} = 4.47 m/s$

5 0

3 years ago

A planet's moon travels in an approximately circular orbit of radius 7.0 ✕ 10⁷ m with a period of 6 h 38 min. Calculate the mass

natka813 [3]

Answer:

3.56×10²⁶ Kg.

Explanation:

Note: The gravitational force is acting as the centripetal force.

Fg = Fc........................... Equation 1

Where Fg = gravitational Force, Fc = centripetal force.

Recall,

Fg = GMm/r²......................... Equation 2

Fc = mv²/r............................. Equation 3

Where M = mass of the planet, m = mass of the moon, r = radius of the orbit and G = Universal gravitational constant.

Substituting equation 2 and 3 into equation 1

GMm/r² = mv²/r

Simplifying the equation above,

M = v²r/G .............................. Equation 4.

The period of the moon in the orbit

T = 2πr/v

Making v the subject of the equation,

v = 2πr/T............................. Equation 5

where r = 7.0×10⁷ m, T = 6 h 38 min = (6×3600 + 38×60) s = (21600+2280) s

T = 23880 s, π = 3.14

v = (2×3.14×7.0×10⁷ )/23880

v = 18409 m/s

Also Given: G = 6.67×10⁻¹¹ Nm²/kg²

Also substituting into equation 4

M = 18409²×7.0×10⁷ /(6.67×10⁻¹¹)

M = 3.56×10²⁶ Kg.

Thus the mass of the planet = 3.56×10²⁶ Kg.

5 0

3 years ago