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3 years ago

Why do you need friction to walk?

Physics

2 answers:

Goshia [24]3 years ago

5 0

Answer:

The force of friction is a necessary force which helps us to walk on ground. The friction is generated between the shoes and the road. We press the ground and as a reaction the ground pushes us forward. The force of friction between sole and ground provides the necessary grip which pushes us forward

Explanation:

Don't copy word for word if your sending as paragraph answer

Ludmilka [50]3 years ago

3 0

Friction can be a useful force because it prevents our shoes slipping on the pavement when we walk and stops car tyres skidding on the road. When you walk, friction is caused between the tread on shoes and the ground. This friction acts to grip the ground and prevent sliding. Sometimes we want to reduce friction.

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A man does 4,475 J of work in the process of pushing his 2.50 103 kg truck from rest to a speed of v, over a distance of 26.0 m.

Tcecarenko [31]

Answer:

a) 1.89 m/s b) 172.1 N

Explanation:

Applying the work-energy theorem, if we can neglect the friction between truck and road, the total change in kinetic energy must be equal to the work done by the external forces.
This work, is just 4,475 J.
So we can write the following equation:

$\Delta K = \frac{1}{2} * m*v^{2} = 4,475 J$

where m= mass of the truck = 2.5*10³ kg.
So, we can find the speed v, as follows:

$v =\sqrt{\frac{2*W}{m}} =\sqrt{\frac{2*4,475J}{2.5e3kg} } = 1.89 m/s$

The work done by the man, is just the horizontal force applied, times the displacement produced by the force horizontally:

$W = F*d$

We can solve for F, as follows:

$F = \frac{W}{d} = \frac{4,475 J}{26.0m} = 172.1 N$

4 0

2 years ago

What type of mixture does the foam demonstrate?

Ksenya-84 [330]

This question doesn't appear to be complete

4 0

3 years ago

A raft with the area A , thickness= h and the mass 600 kg, Floats in still water with 7 cm

elena55 [62]

In this problem, we need to solve for Bubba’s mass. To do this, we let A be the area of the raft and set the weight of the displaced fluid with the raft alone as ρwAd1g and ρwAd2g with the person on the raft, where ρw is the density of water, d1 = 7cm, and d2= 8.4 cm. Set the weight of displaced fluid equal to the weight of the floating objects to eliminate A and ρw then solve for m.

ρwAd1g = Mg

ρwAd2g = (M + m) g

d2∕d1 = (M + m)/g

m = [(d2∕d1)-1] M = [(8.4 cm/7.0 cm) - 1] (600 kg) =120 kg

This means that Bubba’s mass is 120 kg.

7 0

3 years ago

What’s the potential difference across a 5.0 ohms resistor that carries a current of 5.0A

vivado [14]

Answer:

The correct answer is B-25 V

Explanation:

We apply Ohm's Law, according to which:

V = i x R

V = 5A x 5Ω

V= 25 V

Being V the potential difference whose unit is the VOLT, i the current intensity (Ampere) and R the electrical resistance (ohm)

3 0

3 years ago

A 0.5-kg ball moving at 5 m/s strikes a wall and rebounds in the opposite direction with a speed of 2 m/s. If the impulse occurs

mart [117]

Given that:

mass of the ball (m) = 0.5 Kg ,

ball strikes the wall (v₁) = 5 m/s ,

rebounds in opposite direction (v₂) = 2 m/s,

time duration (t) = 0.01 s,

Determine the force (F) = ?

We know that from Newton's II law,

F = m. a Newtons

(velocity acting in opposite direction, so a = ( (v₁ + v₂)/t

= m × (v₁ + v₂)/t

= 0.5 × (5 + 2)/0.01

= 350 N

The force acting up on the ball is 350 N

6 0

3 years ago