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2 years ago

A car drives around a racetrack for 30 seconds. What do you need to know to

Physics

1 answer:

Irina18 [472]2 years ago

3 0

To calculate the average speed of the car, we need

B. The total distance driven on the racetrack

Explanation:

The average speed of an object in motion is given by

$speed = \frac{d}{t}$

where

d is the distance covered by the object

t is the time interval considered to calculate the speed

The SI units of the speed are metres per second (m/s).

In this problem, we know the time interval:

t = 30 s

Therefore, in order to find the average speed, by looking at the equation we see that we also need the total distance driven by the car, so the correct answer is

B. The total distance driven on the racetrack

Learn more about speed:

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Three balls are in water. Ball 1 floats, with half of it exposed above the water level. Ball 2, with a density less than the den

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Answer:

The magnitude of buoyancy force is equal to that of ball's weight.

Explanation:

Ball 1 is floating on water. Weight of ball 1 is Fg=m1g is acting vertically downward

Force of buoyancy FB = ρVdisg is acting vertically upward.

Net force acting on the ball is zero, FB=Fg

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A child blows a leaf straight up in the air from rest. The leaf accelerates at 1.0\,\dfrac{\text m}{\text s^2}1.0 s 2 m1, point,

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Answer:

Time taken by the leaf to displace by 1.0 m distance is

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As we know that initial velocity of the leaf is given as

$v_i = 0$

now the acceleration upwards for the leaf is

$a = 1 m/s^2$

The displacement of leaf in upward direction is

d = 1 m

so now we have

$d = v_i t + \frac{1}{2}at^2$

$1 = 0 + \frac{1}{2}(1) t^2$

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29. 2072 Set C Q.No. 10c

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Answer:

$90.2^{\circ}C$

Explanation:

Considering the thermal conductivity of aluminium and brass as $k_{al}=205 W/mK$ and $k_{br}=109 W/mk$ respectively

The temperature at the end of aluminium and brass are given as $T_{al}=150^{\circ}C$ and $T_{br}=20^{\circ}C$ respectively with length of rod L=1.3 m , Length of aluminium $L_{al}=0.8 m$ , length of brass $L_{br}=0.5 m$ and letting temperature at steady state be T

At steady state, thermal conductivity of both aluminium and brass are same hence

$H_{br}=H_{al}$

$k_{al}A\frac {T_H-T}{L_{al}}= k_{br}A\frac {T-T_H}{L_{br}}$

Upon re-arranging

$T=\frac {k_{al}L_{al}T_{br}+k_{al}L_{br}T_{al}}{k_{br}L_{al}+k_{al}L_{br}}$

$(205)\frac {150-T}{0.8}=109\frac {T-20}{0.5}$

$T=\frac {(109*0.8*20)+(205*0.5*150)}{(109*0.8)+(205*0.5)}$

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Therefore, the temperatures at which the metals are joined is $90.2^{\circ}C$

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2 years ago

Susan and Hannah are each riding a swing. Susan has a mass of 25 kilograms, and Hannah has a mass of 30 kilograms. Susan’s swing

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Answer:

Kinetic energy is given by:

K.E. = 0.5 m v²

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Velocity with which Susan moves is, v = 10 m/s

Hannah has mass, m' = 30 kg

Velocity with which Hannah moves is, v' = 8.5 m/s

Kinetic energy of Susan:

0.5 m v² = 0.5 × 25 kg × (10 m/s)² = 1250 J

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Susan's kinetic energy is 1250 J and Hannah's kinetic energy is 1083.75 J.

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