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2 years ago

1.A car goes off a cliff horizontally at 49 m/s and falls for 5 seconds

1 answer:

3 0

#1). The horizontal speed doesn't change.
The vertical speed is accelerated by gravity.

a). Gravity increases the vertical speed by 9.8m/s every sec.
After 5 sec, the car is falling (5x9.8) = 49 m/s vertically.

b). Horizontal: 49m/s ! Wow ! Almost 110 mph. No wonder he went off the cliff.
After 5 seconds, it's still 49 m/s.

c). After 5 sec, the horizontal speed and vertical-down speed are both 49 m/s.
The combination results in a velocity that points 45 degrees down from horizontal,
and its magnitude is

square root of (49² + 49²) = 49 √2 = about 69.3 m/s .

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Explanation:

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Distance = (120m/s)/4.0s

= (120m/s) / 4.0s

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2 years ago

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2 years ago

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A car starts out traveling at 35 m/s. The car hits the brakes and decelerates at a rate of 3 m/s^2 for 5 seconds. What Distance

Ipatiy [6.2K]

Answer:

Time needed: 2.5 s
Distance covered: 31.3 m

Explanation:

I'll start with the distance covered while decelerating. Since you know that the initial speed of the car is 15.0 m/s, and that its final speed must by 10.0 m/s, you can use the known acceleration to determine the distance covered by

v2f=v2i−2⋅a⋅d

Isolate d on one side of the equation and solve by plugging your values

d=v2i−v2f2a

d=(15.02−10.02)m2s−22⋅2.0ms−2

d=31.3 m

To get the time needed to reach this speed, i.e. 10.0 m/s, you can use the following equation

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t=vi−vfa

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2 years ago

(NEED HELP PLEASE) A physics student goes to the roof of the school, 24.15 m above the ground, and drops a pumpkin straight down

slavikrds [6]

Answer:

t = 2.2 s

Explanation:

Given that,

Height of the roof, h = 24.15 m

The initial velocity of the pumpkin, u = 0

We need to find the time taken for the pumpkin to hit the ground. Let the time be t. Using second equation of kinematics to find it as follows :

$h=ut+\dfrac{1}{2}at^2$

Here, u = 0 and a = g

$h=\dfrac{1}{2}gt^2\\\\t=\sqrt{\dfrac{2h}{g}} \\\\t=\sqrt{\dfrac{2\times 24.15}{9.8}} \\\\t=2.22\ s$

So, it will take 2.22 s for the pumpkin to hit the ground.

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2 years ago

1. 1500j of work was done to move a box 20m. What force was applied to the box ?

Fantom [35]

Answer:

1. 75N

2. 67,983 J (=67.98 kJ)

Explanation:

1. Work = Force x Distance

we are given that Work = 1,500J and Distance = 20m

hence,

Work = Force x Distance

1,500 = Force x 20

Force = 1,500 ÷ 20 = 75N

2. Potential Energy, PE = mass x gravity x change in height

we are given that mass = 165 kg and change in height = 42m

assuming that gravity, g = 9.81 m/s²

Potential Energy, PE = mass x gravity x change in height

Potential Energy, PE = 165 x 9.81 x 42 = 67,983 J (=67.98 kJ)

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3 years ago