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2 years ago

5

A school bus covers a distance of 7200 m in 1800 s. Calculate its speed.

1 answer:

telo118 [61]2 years ago

8 0

Answer:

Speed = 4 m/sec

Explanation:

Speed = Distance / Time

Where Distance = 7200 m and Time = 1800 s

Speed = 7200 m / 1800 sec

Speed = 4 m/sec

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A packing crate with mass 80.0 kg is at rest on a horizontal, frictionless surface. At t = 0 a net horizontal force in the +x-di

Nataly [62]

Answer:

Final speed of the crate is 15 m/s

Explanation:

As we know that constant force F = 80 N is applied on the object for t = 12 s

Now we can use definition of force to find the speed after t = 12 s

$F . t = m(v_f - v_i)$

so here we know that object is at rest initially so we have

$80 (12) = 80( v_f - 0)$

$v_f = 12 m/s$

Now for next 6 s the force decreases to ZERO linearly

so we can write the force equation as

$F = 80 - \frac{40}{3} t$

now again by same equation we have

$\int F .dt = m(v_f - v_i)$

$\int (80 - (40/3)t) dt = 80(v_f - 12)$

$80 t - \frac{40t^2}{6} = 80(v_f - 12)$

put t = 6 s

$480 - 240 = 80(v_f - 12)$

$v_f = 12 + 3$

$v_f = 15 m/s$

6 0

2 years ago

What force is acting on the rainwater in the model?

Vikki [24]

The force is gravitational because when something is falling is call gravitational

8 0

2 years ago

Read 2 more answers

Two cars start 200 m apart and drive toward each other at a steady 10 m/s. On the front of one of them, an energetic grasshopper

vladimir1956 [14]

Answer:

Total distance does the grasshopper travel before the cars hit is 150 m

Explanation:

Each car moves x=100 m before they collide. Both the cars moving in constant velocity. time taken t by each car is

$t=\frac{x}{v}$

where x is the distance traveled with velocity v

$t=\frac{100}{10}\\t=10 sec$

The insect is moving through this time period with a constant velocity of 15 m/s

The distance traveled by grasshopper is

$distance=V_{gh} \times t\\distance=15 \times 10\\distance=150 m$

7 0

2 years ago

A light ray strikes a plane mirror at an angle of 23° to the normal. What is the angle between the reflected ray and the mirror?

tiny-mole [99]

Answer: $67^{\circ}$

Explanation:

Given

Ray of light incident on plane making an angle of $23^{\circ}$ with normal

Thus incident angle $i=23^{\circ}$

So according to the law of incidence is equal to angle of reflection

$\angle i=\angle r$

thus $\angle r=23^{\circ}$

and angle between mirror and reflected ray $=90^{\circ}-23^{\circ}$

$=67^{\circ}$

4 0

2 years ago

Experiments using "optical tweezers" measure the elasticity of individual DNA molecules. For small enough changes in length, the

GalinKa [24]

Answer:

Spring constant, k = 0.3 N/m

Explanation:

It is given that,

Force acting on DNA molecule, $F=1.5\ nN=1.5\times 10^{-9}\ N$

The molecule got stretched by 5 nm, $x=5\times 10^{-9}\ m$

Let k is the spring constant of that DNA molecule. It can be calculated using the Hooke's law. It says that the force acting on the spring is directly proportional to the distance as :

$F=-kx$

$k=\dfrac{F}{x}$

$k=\dfrac{1.5\times 10^{-9}\ N}{5\times 10^{-9}\ m}$

k = 0.3 N/m

So, the spring constant of the DNA molecule is 0.3 N/m. Hence, this is the required solution.

8 0

2 years ago