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3 years ago

A bicyclist is travelling at 25 m/s when he begins to decelerate at -4m/s2 . How fast is travelling after 5 seconds

Physics

1 answer:

Umnica [9.8K]3 years ago

7 0

Initial velocity (Vi) = 25 m/s

acceleration (a) = $-4 m/s^{2}$

time interval (t) = 5 sec

let us assume that final velocity after 5 sec be Vf

As acceleration is constant, we can apply the the equation of motion with constant acceleration i.e. $V_{f} = V_{i} + at$

Hence, $V_{f} = 25 +(-4)(5) = 25 -20 = 5 m/s$

so, the velocity of bicyclist will be 5 m/s after 5 sec

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3 years ago

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A load of 102 kg is support Length 2m and cross-setional area 0.1 cm² the wirers stretched by 0.22cm Find The Tensile strain and

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Answer:

Given, length of wire, l = 2m

cross sectional area , A = 10^-4 m²

Load , F = 102kgwt = 102 × 9.8 N

extension of wire, ∆l = 0.1cm = 0.001m

Longitudinal stress = F/A

= 102 × 9.8/(10^-4)

= 999.6 × 10^4 ≈ 1 × 10^7 N/m²

Longitudinal strain. = extension of wire/original length of wire = ∆l/l

= 10^-3/2 = 5 × 10^-4

we know, Young's modulus = longitudinal stress/longitudinal strain

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Explanation:

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2 years ago

a ball (mas .40) is initially moving to the left at 30m/s. After hitting the wall, the ball is moving to the right at 20 m/s. Wh

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Answer:

The impulse is -20kg m/s.

Explanation:

given mass of ball = 0.4 kg

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The momentum in left direction P1 = mv1

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= 12 kg m/s

The given velocity towards right = -20 m/s ( negative sign shows inverse direction)

Momentum towards right, P2 = mv2

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The Impulse = change in momentum

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3 years ago

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2 years ago

The temp of equal masses of three different liquids A,BandC are 12°C,19°Cand 28°Crespectively . The temp when A and B are mixed

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Answer:

19.1°C

Explanation:

If A and B mix to give 16°C, A has risen by 4°C and B has fallen by 3°C;

If B and C mix to give 23°C, B has risen by 3°C and C has fallen by 5°C;

This means the energy transfered to cause a change of 3°C in B causes a change of 4°C in A and 5°C in C;

We can use this as a ratio (4:5);

The temperature difference between A and C is 16°C;

we add the two parts of the ratio (4+5) to get 9 and divide the temperature difference to get 16/9;

Next we multiply this by one of the parts of the ratio, so with 4, you get 64/9;

This number is the proportional temperature change in A upon mixing;

We then add this to the original temperature of A to get the resultant temperature of the mix like so:

64/9 + 12 = 19.1111...

You can do this alternatively using the other part of the ratio;

We would multiply the 16/9 by the 5 instead of the 4 to get 80/9;

This number is the proportional change in temperature in C upon mixing

Then subtract this from this from the original temperature of C and you should get the same answer:

28 - 80/9 = 19.1111...

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3 years ago