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4 years ago

A shopping cart rolls from x=19.9m to x=5.40m with an average velocity of -0.418m/s. How much time did it take? (unit=s)

Physics

1 answer:

andrew11 [14]4 years ago

8 0

Given

initial position = Xi= 19.9m

Final position Xf = 5.4m

Average velocity= Va = -0.418m/s

it shows displacement is reverse.

To find t=?

As Va = (Xf- Xi) / t

t = (Xf-Xi) / ( Va)

t = ( 5.4-19.9) / (-0.418)

t = (-14.5 ) / (-0.418) (-ve sign cancel out at numerator and denominator)

t =34.69 s

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From the edge of a cliff, a 0.46 kg projectile is launched with an initial kinetic energy of 1430 J. The projectile's maximum up

wel

Answer:

Explanation:

Given

mass of Projectile(m)=0.46 kg

Initial Kinetic Energy=1430 J

Maximum upward displacement from Launch point=150 m

$K.E.=\frac{mv^2}{2}$

$1430\times 2=0.46\times v^2$

v=78.85 m/s

and $H_{max}=\frac{v^2\sin ^2\theta }{2g}$

$150=\frac{(78.85)^2\sin ^2\theta }{2\times 9.8}$

$\sin \theta =0.687$

$\theta =43.39^{\circ}$

initial horizontal velocity $(v_x)=v\cos \theta$

$v_x=78.84\times \cos (43.39)=57.29 m/s$

Initial vertical velocity $(v_y)=v\sin \theta$

$v_y=78.85\times \sin (43.39)$

$v_y=54.16 m/s$

(c)vertical velocity at any instant=65 m/s

Since initial vertical velocity is 54.16 m/s

so 65 m/s will be acquired when projectile started falling below cliff

$v^2-u^2=2 a s$

$65^2-54.16^2=2\times 9.8\times s$

$s=65.90 m$

7 0

3 years ago

Luis is trying to push a box of new soccer balls across the floor. In the illustration, the arrow on the box is a vector represe

solong [7]

Answer:

Complete question

Luis is trying to push a box of new soccer balls across the floor.

If the box is not moving, which of the following must be true?

A. The box is exerting a larger force on Luis than he is exerting on the box

B. There is another force acting on the box that balances Luis's force.

C. Luis is applying a force that acts at a distance.

D. There is no force of friction acting on the box.

Explanation:

Using newton second law of motion

ΣF = ma

Now, for a body not to move when a force is acting on it means that the body is in equilibrium and acceleration a = 0

Therefore,

Fnet = 0

So, if he is applying a force F to push the box and the box is not moving then, there is an external force that is pushing the force back opposite the direction he his pushing and this force counterbalance is own force.

F—F' = 0

F' = F

So, F' is the counter balance force and it is equal to the force applied by Luis

Or it might be frictional force, because if the static friction is not overcome, then, the body will not leave it's state of rest. So if the fictional force is very high, then the box will not leave it rest position and we also know that frictional force opposes motion,

F—Fr=0

F = Fr

So using this explanation,.

The answer is B

B. There is another force acting on the box that balances Luis's force.

3 0

3 years ago

A wave is traveling at a speed of

Digiron [165]

Answer: 5Hz
Explanation: Frequency = Wave speed divided by wavelength.

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3 years ago

A weightlifter lifts a set of weights a vertical distance of 2 meters. If a constant net force of 350 N is exerted on the weight

o-na [289]

Answer:

The work done by the weightlifter, W = 700 J

The power of the weightlifter, P = 350 watts

Explanation:

A weightlifter lifts a set of weights a vertical distance, s = 2 m

The force exerted to lift the weight, F = 350 N

The work done by the body is defined as the product of the force applied by the body to the displacement it caused.

W = F x s

= 350 N x 2 m

= 700 J

The work done by the weightlifter, W = 700 J

The time taken by the weightlifter to lift the weight, t = 2 s

The power is defined as the rate of body to do work. It is given by the equation,

P = W / t

= 700 J / 2 s

= 350 watts

Hence, the power of the weightlifter, P = 350 watts

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3 years ago

A negative velocity, approaching zero, represents a negative acceleration. True or False

ruslelena [56]

Answer:

False.

Explanation:

Lets assume our positive direction to the right (this reasoning works for any direction). A negative velocity would then be then directed to the left. If it varies as such that it aproaches to zero, it means that the variation is directed to the right, and that is where the direction of the acceleration must be pointing. In other words, its losing its velocity, so the acceleration must point opposite to the velocity. Then it means the acceleration is positive.

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4 years ago