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Valentin [98]
3 years ago
9

A 2000kg car experiences a braking force of 10000N and skids to a stop in 6 seconds. The speed of the car just before the brakes

were applied was
A) 45 m/s
B) 15 m/s
C) 1.2 m/s
D) 30 m/s
E) none of these
So far I got a= 5m/s^2 and u= 30m/s but I think the answer is 45 m/s but I do not know where to go from there.
Physics
1 answer:
mylen [45]3 years ago
4 0

Answer:

D. 30m/s

Explanation:

According to the equation of motion

v=u +at

v = Final velocity

u = initial velocity

a = acceleration

t = time taken

Since we don't know the acceleration of the body, we will find its acceleration using newtons first law of motion F = ma

10000 =2000a

a = 5m/s²

initial velocity = 0m/s since the body starts from rest

v is what we are looking for

t = 6seconds

Substituting this datas in the formula

v = 0+ 5(6)

v = 30m/s (D)

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A car is strapped to a rocket (combined mass = 661 kg), and its kinetic energy is 66,120 J.
aliina [53]

Answer:

9.43 m/s

Explanation:

First of all, we calculate the final kinetic energy of the car.

According to the work-energy theorem, the work done on the car is equal to its change in kinetic energy:

W=K_f - K_i

where

W = -36.733 J is the work done on the car (negative because the car is slowing down, so the work is done in the direction opposite to the motion of the car)

K_f is the final kinetic energy

K_i = 66,120 J is the initial kinetic energy

Solving,

K_f = K_i + W = 66,120 + (-36,733)=29,387 J

Now we can find the final speed of the car by using the formula for kinetic energy

K_f = \frac{1}{2}mv^2

where

m = 661 kg is the mass of the car

v is its final speed

Solving for v, we find

v=\sqrt{\frac{2K_f}{m}}=\sqrt{\frac{2(29,387)}{661}}=9.43 m/s

3 0
3 years ago
What is work? How much work is done to move an object 0 meters?
yKpoI14uk [10]
Work is equal to distance times time so no work
7 0
3 years ago
A 6kg sled sliding on an icy surface experiences a 6-N frictional force exerted by the ice and the air resistive force of 0.6 N.
White raven [17]

The net force on the sled is 6.6 N pointing backwards, opposite to the direction it's sliding. That's why it's slowing down, and will eventually stop.

5 0
3 years ago
An engineer weighs a sample of mercury (ρ = 13.6 × 103 kg/m3 ) and finds that the weight of the sample is 6.0 n. what is the sam
Amanda [17]
Given:
ρ = 13.6 x 10³ kg/m³, density of mercury
W = 6.0 N, weight of the mercury sample
g = 9.81 m/s², acceleration due to gravity.

Let V =  the volume of the sample.
Then
W = ρVg
or
V =  W/(ρg)
   = (6.0 N)/[(13.6 x 10³ kg/m³)*(9.81 m/s²)]
   = 4.4972 x 10⁻⁵ m³

Answer: The volume is 44.972 x 10⁻⁶ m³
5 0
3 years ago
A red laser from the physics lab is marked as producing 632.8-nm light. When light from this laser falls on two closely spaced s
BARSIC [14]

Answer:

The wavelength is  \lambda_R  =  649 *10^{-9}\ m

Explanation:

From the question we are told that

   The wavelength of the red laser is  \lambda_r  =  632.8 \ nm =  632.8 *10^{-9}\ m

    The spacing between  the fringe is  y_r  =  6.00\ mm =  6.00*10^{-3}  \  m

   The spacing between  the fringe for smaller laser point  is  y_R   = 6.19 \ mm =  6.19 *10^{-3} \  m

      Generally the spacing between  the fringe is mathematically represented as

       y  =  \frac{D *  \lambda  }{d}

Here  D is the distance to the screen

    and  d is the distance of the slit separation

Now for both laser red light light and  small laser  point  D and  d are same for this experiment

So

         \frac{y_r}{\lambda_r}  =  \frac{D}{d}

=>      \frac{y_r}{\lambda_r}  = \frac{y_R}{\lambda_R}

Where \lambda_R  is the wavelength produced by the small laser pointer

  So

           \frac{6.0 *10^{-3}}{ 632.8*10^{-9}}  = \frac{ 6.15 *10^{-9}}{\lambda_R}

=>       \lambda_R  =  649 *10^{-9}\ m

7 0
3 years ago
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