Please help me.

A horse running at 3 m/s speeds up with a constant acceleration of 5 m/s2. How fast is the

Elan Coil [88]

Answer:

The horse is going at 12.72 m/s speed.

Explanation:

The initial speed of the horse (u) = 3 m/s

The acceleration of the horse (a)= 5 m/ $s^{2}$

The displacement( it is assumed it is moving in a straight line)(s)= 15.3 m

Applying the second equation of motion to find out the time,

$s=ut+\frac{1}{2}at^{2}$

$15.3=3t+2.5t^{2}$

$2.5t^{2}+3t-15.3=0$

Solving this quadratic equation, we get time(t)=1.945 s, the other negative time is neglected.

Now applying first equation of motion, to find out the final velocity,

$v=u+at$

$v=3+1.945*5$

$v=3+9.72$

v=12.72 m/s

The horse travels at a speed of 12.72 m/s after covering the given distance.

7 0

3 years ago

A 78.5-kg man is standing on a frictionless ice surface when he throws a 2.40-kg book horizontally at a speed of 11.3 m/s. With

kirill [66]

Answer:

The man moves across the ice with a speed of 0.345m/s.

Explanation:

From the conservation of linear momentum, we have that the total linear momentum before the book throw is equal to the total linear momentum just after it. Since the initial velocity of the system is zero (so the initial momentum is zero), we have that:

$m_mv_m+m_bv_b=0\\\\v_m=-\frac{m_b}{m_m} v_b$

Where $m_m$ is the mass of the man, $m_b$ is the mass of the book, and $v_m$ and $v_b$ are their velocities. Plugging in the given values, we can compute the speed of the man (ignoring the negative sign, because we care about the magnitude, not the direction):