Physics Final Review 1

On the displacment vs. time graph, Which best describes the velocity of the object?

• The velocity increases at the constant rate.

• The velocity remains the same.

• The velocity decreases at a constant rate.

• The velocity marinas at zero.

 

What can be concluded about the shape of an acceleration vs. time graph when the instantaneous acceleration of an object and its average acceleration are the same?

• It is a curved line.

• It is a zigzag line.

• It is a straight line parallel to the time axis.

• It is a straight line parallel to the acceleration axis.

 

A car traveling at 6.1 m/s increase its speed to 36.5 m/s in 9.9 s. What assumption can be made about the acceleration of the car?

• The instantaneous acceleration of the car is 2.2 m/s/s

• The average acceleration of the car is 3.1 ma/s/s

• The instantaneous acceleration of the cat is 3.7 m/s/s

•   The average acceleration of the car is 4.3 m/s/s

A stone is dropped into water from a bridge 52m above the water’s surface. What ca be determined about the stone when it reaches the water?

• Its mass is 16 Kg

• Its velocity is -45 m/s

• Its speed is 32 m/s

• Its acceleration is -23 m/s/s

Answer explanation

Accelerated = g = 9.8 m/s/s

Vi = 0 (stone is dropped)

D_y = 52 m

Best kinematics equation:

V² = V_i² + 2D_yg

Do not Forget to solve for the value of V not V²

A 100 N force accelerates an object with 5 m/s/s. What is the mass of the object?

• 20 Kg

• 500 Kg

• 0.05 Kg

Answer explanation

Newton's Second Law of Motion: F = m _x a

F = 100 N

a = 5 m/s/s

m= F/a ==>

m = 100 N / 5 m/s/s = 20 Kg

Two different forces act on an object moving on a frictionless surface

What amount of force is moving the object?

• 30 N right

• 60 N right

• 15 N left

• 90 N right

A car travels around a curved track. It moves twice as fast the second time around the track, at compared to the first time. What can be concluded about the centripetal force as the car travels around the track for the second time?

• The centripetal force is one – fourth the original amount.

• The centripetal force is one – half the original amount.

• The centripetal force is twice the original amount.

• The centripetal force is four times the original amount.

Answer explanation

Fc = mV²

r

Centripetal force is directly proportional to V ².

There fore Force will be increase by 4.

An object moves in uniform circular motion. What is the true regarding the force on the object?

• The direction is away from the center, and its magnitude varies.

• The direction is toward the center, and its magnitude varies.

• The Direction is away from the center, and its magnitude is constant.

• The direction is toward the center, and its magnitude is constant

Answer explanation

The direction of centripetal force is always toward the center.

Since the movement is uniform, that means that the magnitude is constant.

Two objects are held close to each other with a compressed spring between them. When the objects are released, one object moves at a speed of 0.63 m/s and the other object moves at a speed of 0.45 m/s. If the faster object has a mass of 0.045 Kg, what is the mass of the slower object?

•      Less than 0.035 Kg  but frater than 0.0 Kg

• Equal to 0.035 Kg

• Greater than 0.035 Kg but less than 0.070 Kg.

• Greater than 0.070 Kg.

Answer explanation

The movement is inelastic.

(m₁+ m₂) v = m₁ v₁ + m₂ v₂

_{Object is at rest 0 =} m₁ v₁ + m₂ v₂

_{m2 =} m₁ v₁

v₂

A box slides on frictionless ice and collides with another box sliding in the same direction. If the two boxes sick together after the collision, what assumption can be made about the type of collision that occurred?

• It was a completely inelastic collision.

• It was an inelastic collision.

• It was an elastic collision

• It was a completely elastic collision.