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andreyandreev [35.5K]
3 years ago
10

A car starts from the rest and retains the acceleration of 4m/S2 in 20 second.calculate its final velocity​

Physics
1 answer:
crimeas [40]3 years ago
5 0

Answer:

80m/s

Explanation:

v=u +at

but the car start from rest so intial velocity (u) =o

therefore,

v=0+4(20)

v=80m/s

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A bird is flying due east. Its distance from a tall building is given by x(t) = 28.0 m + (12.4 m/s)t – (0.0450 m/s3)t3. What is
Kruka [31]

Answer:

3.76 m/s

Explanation:

Instantaneous velocity: This can be defined as the velocity of an object in a non uniform motion. The S.I unit is m/s.

v' = dx(t)/dt..................... Equation 1

Where v' = instantaneous velocity, x = distance, t = time.

Given the expression,

x(t) = 28.0 m + (12.4 m/s)t - (0.0450 m/s³)t³

x(t) = 28 + 12.4t - 0.0450t³

Differentiating x(t) with respect to t.

dx(t)/dt = 12.4 - 0.135t²

dx(t)/dt = 12.4 - 0.135t²

When t = 8.00 s.

dx(t)/dt = 12.4 - 0.135(8)²

dx(t)/dt = 12.4 - 8.64

dx(t)/dt = 3.76 m/s.

Therefore,

v' = 3.76 m/s.

Hence, the instantaneous velocity = 3.76 m/s

8 0
3 years ago
Two bicycle tires are set rolling with the same initial speed of 3.30 m/s along a long, straight road, and the distance each tra
vredina [299]

Answer:

At low pressure- \mu_{k}=0.02315

At high pressure- \mu_{k}=0.00445

Explanation:

Initial speed, V_{i}=3.3 m/s

Final speed, V_{f}=3.3/2= 1.65 m/s

Net horizontal force due to rolling friction F_{net}=\mu_{k} mg where m is mass, g is acceleration due to gravity, \mu_{k} is coefficient of rolling friction

From kinematic relation, V_{f}^{2}- V_{i}^{2}=2ad

For each tire,

V_{f}^{2}- V_{i}^{2}=2\mu_{k}gd

Making \mu_{k} the subject

\mu_{k}=\frac {V_{f}^{2}- V_{i}^{2}}{2gd}

Under low pressure of 40 Psi, d=18 m

\mu_{k}=\frac {1.65^{2}- 3.3^{2}}{2*9.8*18}=-0.02315

Therefore, \mu_{k}=0.02315

At a pressure of 105 Psi, d=93.7

\mu_{k}=\frac {1.65^{2}- 3.3^{2}}{2*9.8*93.7}=-0.00445

Therefore, \mu_{k}=0.00445

4 0
3 years ago
Martina seems to have several different personalities. In one, she is 7 years
melomori [17]

Answer:Dissociative Identity Disorder

Explanation:I don't say you have to mark my ans brainliest but my friend if it has really helped you don't forget to thank me...

3 0
3 years ago
Which of the following supports the theory of continental drift?
Y_Kistochka [10]
I think it's The fossil record. The same animal fossil is in Africa and South America. The animal could have not swim across so its the fossil record
7 0
3 years ago
The Burj Khalifa in Dubai is the world's tallest building. The structure is 828 m 828 m (2716.5 ft) and has more than 160 storie
Natasha_Volkova [10]

Answer:

h = height of the hotel room from the ground floor = 237.4m

Explanation:

Change in Potential Energy of tourist = ΔPE = PE2 – PE1 = mgh

PE1 is the potential energy of tourist at the ground floor

PE1 is the potential energy of tourist at the top (hotel room)

Given

PE1 = − 2.01 × 10⁵ J

PE2 = 0J

PE2 – PE1 = mgh

0 – (− 2.01 × 10⁵ J) = mgh

2.01 × 10⁵ J = 86.4×9.8×h

h = 2.01 × 10⁵/(86.4×9.8) = 237.4m

8 0
3 years ago
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