All categories

3 years ago

A car traveling at 30m/s screeches to a halt, leaving 55 m long skid marks. what was the cars acceleration while braking

1 answer:

6 0

For this problem we use the derived equations for rectilinear motion at constant acceleration. The equation is written below:

2ax = v² - v₀²
where
a is the acceleration
x is the distance
v is the final velocity
v₀ is the initial velocity

Since the car comes to a stop eventually, v=0. Substituting the values,

2a(55) =0² - 30²
a = -8.18 m/s²

You might be interested in

considere que o calor específico de um material presente nas cinzas seja c=0,8j/gc. Supondo que esse material entre na turbina a

drek231 [11]

Answer:

3120J

Explanation:

Given parameters:

C = Specific heat capacity = 0.8J/g°C

Initial temperature = 20°C

Mass given = 5g

Final temperature = 800°C

Unknown:

Energy given to the mass = ?

Solution:

To find the energy given to the mass, let us simply use the expression below:

H = m c ΔT

H is the unknown, the energy supplied

m is the mass of the substance

c is the specific heat capacity

ΔT is the change in temperature

Input the variables;

H = 5 x 0.8 x (800 - 20) = 3120J

7 0

3 years ago

What is needed to set a body in motion

kumpel [21]

Answer:

Newtons law

Explanation:

According to this law, a body at rest tends to stay at rest, and a body in motion tends to stay in motion, unless acted on by a net external force.

3 0

3 years ago

If an object absorbs all colors but red, we see

julia-pushkina [17]

[I researched for you, since I am not in that particular level to know that knowledge yet. I assure this is accurate info :)]

The answer is A, red.
"Remember, the color you see is light REFLECTING off the surface of that object. If all colors are absorbed in to the surface EXCEPT red, red must be reflected, and you'll see red." - Yahoo User @Chap

8 0

2 years ago

A 125-kg astronaut (including space suit) acquires a speed of 2.50 m/s by pushing off with her legs from a 1900-kg space capsule

ryzh [129]

(a) 0.165 m/s

The total initial momentum of the astronaut+capsule system is zero (assuming they are both at rest, if we use the reference frame of the capsule):

$p_i = 0$

The final total momentum is instead:

$p_f = m_a v_a + m_c v_c$

where

$m_a = 125 kg$ is the mass of the astronaut

$v_a = 2.50 m/s$ is the velocity of the astronaut

$m_c = 1900 kg$ is the mass of the capsule

$v_c$ is the velocity of the capsule

Since the total momentum must be conserved, we have

$p_i = p_f = 0$

$m_a v_a + m_c v_c=0$

Solving the equation for $v_c$ , we find

$v_c = - \frac{m_a v_a}{m_c}=-\frac{(125 kg)(2.50 m/s)}{1900 kg}=-0.165 m/s$

(negative direction means opposite to the astronaut)

So, the change in speed of the capsule is 0.165 m/s.

(b) 520.8 N

We can calculate the average force exerted by the capsule on the man by using the impulse theorem, which states that the product between the average force and the time of the collision is equal to the change in momentum of the astronaut:

$F \Delta t = \Delta p$