Question

1. a truck is sitting at rest at a red light. when the light turns green the driver hits the gas, giving the truck a constant acceleration equal to 2.6 m/s². after the car has been accelerating for 8.0 seconds, what is its velocity equal to?

a. 20.8 m/s
b. 20.6 m/s
c. 30.2 m/s
d. 33.0 m/s
e. 18.4 m/s

1. a ball falls through the air in the absence of air resistance. which free - body diagram represents the forces acting on the ball?

a. diagram with a ball and a downward force fg
b. diagram with a ball and a horizontal force fa and a downward force fg
c. diagram with a ball and an upward force fa and a downward force fg
d. diagram with a ball and horizontal forces fl and fr and an upward force fa and a downward force fg

1. an ice skater glides across a frictionless rink moving with a constant speed in a straight line to the right. which of the following free - body diagrams would describe the forces acting on the skater as they glide across the ice? b

a. diagram with a ball and a horizontal force fa
b. diagram with a ball and an upward normal force fn and a downward force mg
c. diagram with a ball and an upward normal force fn, a downward force mg and a horizontal force fnc
d. diagram with a ball and an upward normal force fn, a downward force mg and a horizontal force fa

1. a ball hangs at rest from a rope. if the rope experiences a tension force of 692.0 newtons, what must be the mass of the ball in kilograms?

a. 692.0 kg
b. 69.2 kg
c. 70.6 kg
d. 98.0 kg
e. 678.1 kg

Explanation:

Question 7

Step1: Recall the velocity - acceleration - time formula

The formula for velocity $v$ in uniformly - accelerated motion is $v = v_0+at$, where $v_0 = 0$ (starts from rest), $a = 2.6\ m/s^{2}$, and $t = 8.0\ s$.
$v=0 + 2.6\times8.0$

Step2: Calculate the velocity

$v=20.8\ m/s$

When a ball falls through the air in the absence of air resistance, the only force acting on it is the force of gravity $F_g$ acting downwards.

An ice - skater gliding across a frictionless rink with a constant speed in a straight line has no net force in the horizontal direction. In the vertical direction, the normal force $F_N$ balances the force of gravity $mg$.

Answer:

a. $20.8\ m/s$

Question 8